patient outcomes with co-managed post-operative care after cataract surgery

J Clio Epidemiol Vol. 46, No. I, pp. 5-15, 1993 0895-4356/93 $6.00 + 0.00 Printed in Great Britain. All rights reserved Copyright 0 1993 Pergamon Press Ltd

PATIENT OUTCOMES WITH CO-MANAGED POST-OPERATIVE CARE AFTER

CATARACT SURGERY*

DENNIS A. REVICKI,~ RUTH E. BROWN and MARINA A. ADLER Battelle Medical Technology Assessment and Policy Research Center, 370 L’Enfant Promenade,

Washington, DC 20024, U.S.A.

(Received in revised form I2 March 1992)

Abstract-This study examined the practice of co-managed post-operative care and the visual acuity outcomes and complications associated with co-managed services. Data on service utilization and medical outcomes were collected for 2822 cataract surgery procedures performed in 5 ambulatory eye centers between January and July 1988. Average age of patients was 72.8 (SD = 10.4) and 63% were female. Eighty-seven percent of eyes were co-managed. Average number of post-operative visits within 90 days was 4.7 and 6.2 for co-managed cases with and without complications, respectively. Successful visual acuity outcomes (< 20/40) were experienced by 86% of all co-managed patients. There was evidence that patients with pre-existing ocular conditions (e.g. glaucoma, macular degeneration) and serious post-surgical complications were not referred for co-management. For co-managed patients without pre-existing medical or ocular conditions, 92% had successful vision outcomes, while 77-90% with these conditions had successful outcomes. Ninety-three percent of co-managed cases had no post-operative complications, and the rate of specific types of complications ranged from 0.04 to 2.0%. Using physician evaluations as the standard, sensitivity of optometrist detection of complications was 59% and specificity was 99.6%. Optometrists located in separate offices demonstrated 95.8% accuracy in assessing patients for post-operative complications.

Co-managed care Cataract surgery complications Optometrists

INTRODUCTION

Cataracts are opacities of the lens and lens capsule of the eye and represent the third lead- ing cause of blindness in the U.S. The prevalence of cataracts ranges from 16.0-19.3 per 1000 in men and women, respectively, aged 65-74 years to 40.9-48.9 per 1000 in men and women, respectively, aged 75-85 years [l, 21. Surgery is the only treatment for cataracts and, therefore, cataract surgery with intraocular lens

*This paper was presented in part at the Seventh AMI& Meeting of the Awociation for Health !hvices Research, Arlington, Virginia, 17-19 June 1990.

TAuthor for correspondence.

visual acuity outcomes Post-operative

(IOL) implant is one of the most frequent surgical procedures performed on elderly individuals [3]. As many as one million cataract surgery procedures are performed each year in the U.S.

Cataract surgery is successful in improving vision for most patients. 81-97% of patients evaluated one year after surgery achieve a 20/40 visual acuity [4-131. However, only 42-75% of patients with pre-existing ocular or medical conditions may achieve 20/40 visual acuity [5,7-9, 11, 14, IS] while 86-98% of patients without any pre-existing condition have visual acuity outcomes of 20/40 or better after cataract surgery [4,5,7-9, 131. These improvements in

6 DENNIS A. REVICKI et al.

vision also may lead to improvements in activi- ties of daily living and mental status [16].

Cataract surgery is not completely without the risk of complications. The most frequently reported complication is cystoid macular edema which is found in 2-16% of patients [4-9, 11, 131. Some of the other post-operative complications reported in the literature for inpatient cataract surgery include endophthalmitis, pupillary block and detached retina [4, 5,7-g, 131.

Over the past 15 years technological advances have occurred in cataract surgery including increased reliance upon posterior chamber IOL, improved microsurgical techniques, and improved anesthesia methods [3, 171. Advances in surgical technology have reduced complication rates and have allowed the transfer of cataract surgery from an inpatient to an outpatient setting for more than 96% of cases [18]. Hen- ning et al. [19] and Bloom and Krueger [20] reported no significant differences in vision outcomes and complications for outpatient versus inpatient cataract surgery. Ophthalmologists are most often responsible for the pre- and post-operative care of cataract patients in the U.S., but with the growth in outpatient cataract surgery, there has been an increased transfer of some post-operative care responsibilities to optometrists.

The Office of Technology Assessment (OTA) examined the medical safety and appropriateness of care for cataract patients when an ophthalmologist performs the surgery and an optometrist, at a separate site, provides the pre-operative evaluation and/or post-operative follow-up [18]. The report discussed cataract surgery complications and noted that good post-operative care is necessary to successfully manage ocular complications and maximize vision outcomes. Differences in the education and training between optometrists and ophthalmologists were examined and, based upon these differences, the report concluded that there may be “potential risks in allowing optometrists the expanded role in providing post-operative care for cataract patients” in settings separate from ophthalmologists’ offices [ 181. However, the conclusions of the OTA paper were based on a review of the cataract surgery literature and clinical training programs and physician opinion. No empirical data were available de- scribing the vision outcomes or complication rates for patients receiving co-managed care following cataract surgery.

This study was designed to examine the practice of co-management by ophthalmologists and optometrists and to examine visual acuity outcomes and post-operative complications for cataract surgery patients receiving co-managed post-operative services. The design of this study precludes making comparisons between co- managed cases and center-managed cases or cases managed entirely by ophthalmologists. Center-managed cases are defined as those cataract surgery patients who receive no post- operative services from optometrists located outside of the ambulatory eye centers. Data on center-managed cases are included to describe characteristics of patients who are not referred for co-management. The ideal research design for comparing co-managed versus ophthalmologist managed post-operative care would be a randomized clinical trial with blind evaluation of medical outcomes. However, this design was considered impractical given the large sample size that would be necessary for adequate stat- istical power and the available resources. There- fore, this study involved the retrospective review of medical records and a comparison of the vision outcomes and complication rates found in co-managed cases versus historical controls from previously published studies.

METHODS

A historical cohort design, involving the retrospective review of medical records for patients undergoing IOL implant cataract surgery in 1988, was used to gather data on patient outcomes. Data on patient demographic and pre-operative ocular and medical conditions, cataract surgery, post-operative services, complications, and visual acuity outcomes were abstracted from medical records.

Population and sample Five non-randomly selected ambulatory eye

centers located in the southeastern and north- western U.S. were identified and asked to participate in the study. The eye centers were selected if they performed a high volume of cataract extractions and IOL implants (>500 annually) and involved optometrists in the delivery of post-operative care. No other centers were identified and all five eye centers elected to participate in the study. The usual staff arrange- ment within each center included one or more board-certified ophthalmologists, two or more optometrists, and various support staff. In these

Co-managed Post-operative Care I

centers, all post-cataract surgery care services were provided by ophthalmologists and optometrists. In general, post-operative services were delivered by a combination of center ophthalmologists and optometrists, and optometrists located outside the center.

Data on consecutive patients having cataract surgery procedures with IOL implant during the 7 month period between 1 January and 31 July 1988 were included in the study. Within each eye center, patients having cataract surgery within the specified time frame were identified from surgical logs by study research assistants. Data on post-operative care and co-management were collected from the medical records. Co- managed care was defined as at least one post- operative care visit to an optometrist outside the center within 90 days following cataract surgery. In practice, 84% of co-managed patients had two or more visits to outside optometrists. Vision outcome and complication rate data for patients receiving only in center post-operative services were not included in this analysis. In cases where bilateral IOL implant cataract surgery was performed, each eye was treated as a separate case. There were no significant differences in visual acuity outcomes whether eyes or patients were used as the unit of analysis. Therefore, only the analyses by eyes will be reported. Throughout the remainder of the report cases will refer to eyes undergoing cataract surgery.

Organization of co -managed services

Co-management involves the coordinated delivery of follow-up services by ophthalmologists and optometrists after cataract surgery. Patients are normally referred by their optometrist to the ophthalmologist for a comprehensive eye evaluation when the need for cataract surgery is suspected. If cataract surgery with an IOL implant is indicated, the surgeon performs the procedure and evaluates the patient at the eye center 1 day and usually 3-6 weeks after surgery. All patients experiencing post-operative complications were seen two or more times by physicians and 54% of patients without problems had a 1 day post-surgery and follow-up evaluation within 90 days. If no immediate post-operative complications were detected and the patient does not have a severe pre-existing ocular condition (e.g. diabetic retinopathy, macular degeneration, glaucoma), the remaining post-operative care is delivered by the referring optometrist. Most patients are referred back to

their optometrist following the l-day post- operative assessment.

The centers participating in this study do not have specific protocols for assigning cases to be co-managed or center-managed. Decisions about co-management are based on the condition of the eye during the l-day post-operative evaluation, the distance of the patient’s resi- dence from the eye center, pre-existing ocular or medical conditions, the qualifications of the outside optometrist, and patient preference.

A regular schedule of post-operative evaluations is provided by the optometrist. When and if complications of cataract surgery develop while the patient is in the care of the optometrist, the optometrist normally handles them after telephone consultation with the center ophthalmologist. Decisions about whether to return the patient to the eye center are based on the seriousness of the complication (e.g. lens dislocation). Otherwise the optometrist follows the patient as necessary until the complication resolves.

The eye centers offer continuing medical education courses for optometrists in the clinical management of cataract surgery patients and require that optometrists participating in co- management take these courses. Optometrists are also required to have essential diagnostic equipment before participating in co-managed care. Close communication is maintained between the centers and the optometrist to ensure that complete post-operative services are provided to patients.

Data collection procedures Data on demographic characteristics, pre-

existing ocular and medical conditions, the surgical procedure for cataract removal, all post-operative services, and post-operative complications and visual acuity outcome measurements, for the 90 days after the surgery, were abstracted from optometrist and eye center medical records. Optometrists participating in co-management submitted reports to the eye center after each examination. The reports de- tailed vision measurements and any post-operative problems that the patient may be having. Within each center, surgical logs were used to identify all cataract procedures occurring during the 7 month study period. Medical record ab- stractors collected information from records using standardized data collection forms. Ques- tions about incomplete data, idiosyncratic ab- breviations, and other data contained in the


records were resolved during the data collection visit. When records with missing vision outcome or other data were identified, center staff contacted the patient’s optometrist and provided the missing data to the investigators.

Demographic characteristics. Age (in years) and gender of patients was abstracted from medical records.

Medical characteristics. Data was collected on the presence of existing ocular conditions (glaucoma, diabetic retinopathy, macular degeneration, cornea guttata/Fuch’s dystrophy) that may be related to visual acuity outcome [21]. Data was also gathered on the presence of several chronic medical conditions (i.e. cardiovascular disease, diabetes mellitus, renal disease, pulmonary disease) as indicators of general health status. Insufficient data were available in the records to classify severity of illness for the ocular or medical conditions. Comorbidity combined with age, preoperative visual acuity, and frequency of reading has been demonstrated to predict surgical success in cataract patients [2 1,221.

Cataract surgery procedure. Information was collected on the type of lens extraction surgery (i.e. intracapsular, extracapsular, or phacoemulsification), the eye operated on, and date of surgery.

Post-operative management. The date, location, and provider of services for each visit within 90 days of surgery was collected for each eye included in the study. The provider of service was either an ophthalmologist or an optometrist. The location of post-operative care was either the center or an optometrist’s office outside the center.

Visual acuity measurements. Pre-operative visual acuity was collected for the patients not achieving a post-operative best visual acuity of 20/40 or better. For the majority of these patients, potential acuity meter and super pin- hole test results were recorded. The corrected visual acuity for each post-operative visit during the 90 days following cataract surgery was gathered from the medical records. Successful vision improvement was defined as a visual acuity of 20/40 or better.

Complications. There are numerous complications which may follow cataract surgery; some are temporary and do not result in im- paired vision, others cause discomfort with little long-term vision effects, while others are serious and may result in decreased vision. Compli- cations, notably cornea1 edema and hemorrhage

in the anterior chamber, frequently occur im- mediately following surgery but resolve spon- taneously [23]. Persistence of these conditions, however, may indicate a serious problem. The medical records were examined to identify the onset of complications which may result in poor visual acuity outcomes. The complications included were: endophthalmitis/hypopyon; chronic uveitis; bullous keratopathy/significant cornea1 edema; secondary glaucoma; wound rupture (e.g. iris prolapse); pupillary block; detached retina; cystoid macular enema; and lens dislocation. For this study, if a complication occurred at any time within 90 days of surgery, it was recorded as present, which is a significantly broader definition and time frame than those used in several previous investigations [5]. Com- plications were recorded as present if there was clear evidence in provider notes and/or test results contained in the medical record.

Data analysis

Descriptive statistics (e.g. means, standard deviations, frequency distributions) were calculated for all study variables. Student’s t-test and chi-square tests were used to evaluate baseline differences between the co-managed and center- managed groups. Best visual acuity outcome within 90 days of cataract surgery was deter- mined and the standard of 20/40 or better was used to define successful vision outcome. Pre- operative potential visual acuity measures were analyzed for patients not achieving a successful vision outcome. Visual acuity outcomes were summarized by patient age, pre-existing diseases, and post-operative complications for co-managed cases. The incidence rate of complications was calculated per 100 cataract surgical procedures for all co-managed cases.

RESULTS

A total of 2390 patients were included in this study. Of these patients, 306 (13%) were center- managed and 2084 (87%) were co-managed. Eighteen percent of the patients had bilateral cataract surgery and IOL implantation during the 7 month study period, which translates into 2822 eyes having cataract surgery (co-managed eyes, 2458; center-managed eyes, 364). Visual acuity outcome data was missing and could not be located for 8.7% of the co-managed cases. The average age of all patients was 72.8 years (SD = 10.4) and 63% of the patients were female. Eighty-eight percent of the cataract

Co-managed Post-operative Care

Table 1. Preoperative characteristics of co-managed and center-managed cataract surgery patients

9

Center-managed Co-managed p Value*

Patients

ige (mean (SD)) 306 70.5 2084 72.9 <O.Ol (12.2) (10.4)

Sex Male (%) 35.6 37.5 NS Female (%) 64.4 62.5

Eyes n 364 2458 Pre-existing eye conditions

Glaucoma (%) 6.9 5.4 NS Diabetic retinopathy (%) 5.2 < 2.6 <O.Ol Macular degeneration (%) 14.8 13.1 NS Cornea guttata (%) 5.5 : 6.1 NS

Pre-existing medical conditions Diabetes mellitus (%) 22.0 16.6 < 0.05 Cardiovascular disease (%) 50.5 55.9 NS Renal disease (%) 1.1 3.5 NS Pulmonary disease (%) 10.7 9.6 NS

*Two-tailed Student t-test or chi-square test.

surgeries involved phacoemulsification procedures while most of those remaining were extracapsular IOL procedures (11%). Less than 1% of the cases were for repeat cataract surgical procedures.

Comparison of center -managed and co -managed cases

The co-managed patients were older than the center-managed patients (Table 1). The sex distributions of the co-managed and center-managed cases were comparable. Fewer co-managed patients had diabetic retinopathy (p < 0.01) or diabetes mellitus (p < 0.05). Slightly more center-managed patients had evidence of glaucoma. There was evidence that the cases managed within the center were at higher risk for poor vision outcomes. Ocular conditions were present before surgery in 50% of the center- managed cases compared with 40% in co-managed cases (p < 0.0005). A greater number of center-managed cases (39%) had both pre-existing ocular and medical conditions compared with co-managed cases (30%) (p < 0.0008). Patients with evidence of serious ocular conditions, such as glaucoma and retinal disease, were less likely to be referred for co- managed care. These differences suggest that the center providers manage the more difficult patients and refer less complicated cases to the outside optometrists for post-surgical care.

Co -managed post -operative care Eighty-seven percent of the eyes were co-man-

aged. A total of 11,921 post-operative visits

(center providers, 4888; outside optometrists, 7033) occurred as part of the management of these co-managed patients following cataract surgery. Optometrists outside the centers delivered 59% of the post-operative care for co-managed eyes. All patients were evaluated by the ophthalmic surgeon 1 day after surgery. All patients with complications had two or more evaluations by physicians. Fifty-four percent of cases without complications were re-evaluated by physicians within 90 days of surgery. Disre- garding the l-day post-operative follow-up, optometrists located outside of the surgical center delivered over 74% of the post-operative care for these eyes.

The average number of post-operative visits was 4.85 (SD = 1.73) for co-managed cases. Thirty percent of cases were seen post-operatively on four occasions, with three of these follow-up examinations conducted by optometrists outside the center. Co-managed cases with evidence of post-operative complications had an average of 6.23 (SD = 2.05) visits compared with 4.73 (SD = 1.64) visits for those without complications. Sixteen percent of cases had one physician and one optometrist post-operative evaluation. Seventy-five percent of cases had 2 or more examinations by optometrists following cataract surgery. Twenty-three percent had two optometrist visits, 34% had three and 18% had four post-operative visits to optometrists.

Visual acuity outcomes Eighty-six percent of all co-managed cases

had final visual acuity of 20/40 or better within


90 days of cataract surgery. Eighty-five percent of co-managed eyes of older patients had successful vision outcomes compared with 91% of those less than 65 years old.

Figure 1 summarizes findings on visual acuity outcome by the presence or absence of pre-existing ocular disease or chronic medical conditions. In the co-managed group without medical or ocular conditions, 92% of cataract surgery procedures resulted in successful vision outcomes. Seventy-seven percent of co-managed cases with ocular conditions and 79% with medical and ocular conditions had visual acuity outcomes of 20/40 or better within 90 days of surgery.

For those cases not achieving final visual acuity of 20/40 or better, we analyzed the pre- operative potential acuity meter or super pin- hole measurements. For the 316 co-managed eyes, 54% had potential visual acuities worse than 20/40 before surgery. In addition, 58% of these cases had both pre-existing medical and ocular conditions. For those eyes with unsuc- cessful vision outcomes, 79% of co-managed eyes had evidence of pre-operative ocular conditions.

Visual acuity outcomes were summarized for co-managed eyes by whether post-operative complications were evident in the medical record. For cases without post-operative complications, a successful vision outcome was ob- served in 87% of co-managed cases. Of the 174 co-managed cases with complications and visual acuity data, 71% achieved a visual acuity outcome of 20/40 or better.

Post-operative complications

Complications occurred in 174 (7.1%) of the co-managed cases. For four cases (2.3%) data was unavailable on post-operative medical services. The center ophthalmologists diagnosed 48 (28.2%) complications before returning the case to an outside optometrist. Optometrists located outside the centers identified 72 (59.0%) of the 122 remaining complications during routine post-operative examinations. For those cases where there were visits to center providers after management by optometrists (n = 122; 71.8% of co-managed cases with complications), additional complications were detected in 50 (41.0%) of these cases. Center ophthalmologists detected 29 (58.0%) and center optometrists

Percent ( 20/40 Visual Acuity 100

NO MEDICAL MEDICAL OR OCULAR CONDITION CoN6)NILTYoN

OCULAR

Co%ilYoN

MEW;A\ND

CONDITION

Fig. 1. Best visual acuity outcomes for co-managed cases by presence of medical or ocular conditions.

Co-managed Post-operative Care II

Table 2. Post-operative complication rate for co-managed cataract surgery eyes (n = 2458)

Complication n (%) Endophthahnitis/hypopyon 1 (0.04) Chronic uveitis 28 (1.1) Bulbus keratopathy/significant

cornea1 edema Secondary glaucoma Wound rupture Pupillary block Detached retina Cystoid macular edema Lens dislocation

49 23 ;:;; 13 (0.5) 11 (0.4) 6

45 :;:;,’ 3 (0.1)

found 21 (42.0%) of these additional complications. The most frequent complications that were found after visits to outside optometrists were cystoid macular edema (34%), bullous keratopathy or significant cornea1 edema (16%), pupillary block (12%) and uveitis (8%). These findings suggest that outside and center optometrists detected 76.2% of the complications occurring after cataract surgery.

There were a total of 1322 cases (54% of all co-managed eyes) where an ophthalmologist examined the eye after management by an outside optometrist. Thirty-six of these cases involved post-surgical complications diagnosed by physicians and treated before referral to optometrists. One hundred and twenty-two of these cases had a post-operative complication based on optometrist or ophthalmologist evaluations. Physicians did not detect complications in any cases that were evaluated as complication free by optometrists. Using ophthalmologist examinations as the gold standard, the sensitivity of outside optometrist detection of complication was 59% and the specificity was 99.6%. The positive predictive value was 94.7% and the negative predictive value was 96%. The

overall accuracy of optometrist assessment of post-operative complications was 95.8%.

Complications for co-managed eyes in the study occurred at rates between 0.04 and 2.0% of cataract surgery procedures (Table 2). The most frequently occurring complications were cystoid macular edema (1.8%) and bullous keratopathy/significant cornea1 edema (2.0%). Endophthalmitis/hypopyon and lens dislocation occurred in less than 0.10% of cases. The incidence of most of the complications was less than 1%. There were no significant differences in the incidence of complications when these analyses were conducted by patients rather than eyes.

We also evaluated the association between pre-existing medical or ocular conditions and occurrence of complications (Table 3). There was evidence that the presence of a medical or ocular condition before surgery increased the risk of a post-operative complication (p = 0.048). When this was examined by indi- vidual complication, there were statistically significant differences for secondary glaucoma (p < 0.001) and for cystoid macular edema (p = 0.044). Cases with existing eye disease were more likely to experience post-operative secondary glaucoma (3.7%) compared with those with no medical or ocular conditions (0.5%) or those with medical conditions (0.8%). It was also found that cases with existing ocular or ocular and medical conditions had a greater incidence of post-operative cystoid macular edema (2.3-2.7%) compared to those without evidence of these conditions (0.7%).

DISCUSSION

This study examined co-managed care and the visual acuity outcomes and incidence of

Table 3. Pre-existing medical and ocular conditions and post-operative complication rates*

No medical or ocular condition

Medical condition

only

Ocular condition

only

Medical and ocular condition p Valuet

n Total complications Endophthalmitis/hypopyon Chronic uveitis Bulbus keratopathy/significant

cornea1 edema Secondary glaucoma Wound rupture Pupillary block Detached retina Cystoid macular edema

593 4.7 0.0 1.2

1.5 0.5 0.7 0.2 0.2 0.7

875 6.7 0.0 1.0

2.1 2.8 2.1 0.696 0.8 3.7 0.6 <O.OOl 0.3 0.5 0.6 0.195 0.6 1.4 0.3 0.096 0.2 0.5 0.3 0.898 1.7 2.3 2.7 0.044

214 9.8

8:X

176 7.6 0.1 1.3

0.048 0.538 0.953

Lens dislocation 0.2 0.1 0.0 0.1 0.945

*Numbers in table are percentage of cases in pre-existing condition categories with complication. tp Value for chi-square test of association between pre-existing condition and presence or absence of

complication.


complications following outpatient cataract surgery. Data on 2458 consecutive cataract surgery procedures involving co-managed post-operative services were collected from five centers and results are reported by eye.

There are several caveats to be considered when interpreting the findings of this study. First, the design was a retrospective cohort study using medical records as primary data sources. Consequently, all problems associated with retrospective data collection from medical records (e.g. missing and incomplete data, different definitions of complications, unstan- dardized visual acuity measurements) are shared by this investigation. It should be noted that some of these problems are found in a number of studies of eye disease epidemiology [24]. Using standardized data collection methods, data were collected for consecutive cataract surgery procedures occurring within a defined time period in the five eye centers. All cases were identified from surgical logs in each of the centers.

Second, the eye centers included in the study were not randomly selected, but were invited to participate based on volume of cataract surgery procedures and use of co-managed post-operative care. The demographic and clinical characteristics of patients in this study are similar to those reported in other studies of cataract surgery outcomes [4,6,9, 161 and cataract epidemiology [l, 21. The average age of individuals with cataracts was 73 years in the Framingham Eye Study compared to 72.8 years in this study. However, in these eye centers, 88% of cataract extractions were done using phacoemulsification, while nationally only 25-30% of cataract extractions are performed using phacoemulsification. Therefore, the results of this investigation may be generalizable only to those type of eye centers performing cataract surgery that are similar in organization and patient population. Data collected in other outpatient surgery setting may find better or worse visual outcomes and higher or lower complication rates.

Third, some loss to follow-up occurred in the eye center medical records. Nine percent of patients had missing or incomplete visual acuity outcome data. This rate of loss to follow-up is comparable to the l-17% reported in previous ophthalmologic studies [5,7, 16,241. There are a number of reasons for incomplete records, including the failure to record follow-up examinations in center and from outside optometrists,

patient non-compliance with follow-up visits, failure to schedule post-operative services, and patient seeking care from alternative sources. Patient non-compliance with scheduled post-operative care may not occur in those patients experiencing a complication because of the discomfort associated with a serious adverse outcome. More likely, patients with successful vision outcomes may not keep appointments because they view additional follow-up evaluations as unnecessary. However, retinal detach- ment and cystoid macular edema may not be associated with discomfort and also may lead to vision loss. Research on compliance with scheduled outpatient visits suggests that 15-35% of patients fail to keep their appointments [25-271. The rate of missed post-operative visits for this study is not excessive compared to rates found in the literature.

Finally, this study was not designed to evaluate the vision outcomes and complication rates for co-managed versus ophthalmologist- managed cataract surgery cases. A randomized clinical trial or other prospective design with attention to comparability of patients and standardized post-operative outcome evaluations would be necessary to compare the two service delivery approaches. The findings cannot be used to compare the outcomes of co-managed to ophthalmologist-managed cases, since the center-managed group contained a greater number of cases with complications and more severe pre-existing ocular diseases, such as diabetic retinopathy, macular degeneration, and glaucoma. Patients with evidence of serious ocular conditions, such as glaucoma and retinal disease, or with post-operative complications were less likely to be referred for co-managed care. In addition, all of the center-managed cases were followed by both ophthalmologists and optometrists working in the eye centers.

Eighty-seven percent of the consecutive patients (and eyes) in the five eye centers were co-managed. Optometrists outside the center delivered 74% of post-operative visits excluding the l-day post-operative evaluation by the surgeon. The findings indicate that cases with pre-existing ocular or ocular and chronic medical conditions were less likely to be referred for co-management. These more complicated patients were followed post-operatively by ophthalmologists and optometrists in the eye center. They were released to outside optometrists only after sufficient follow-up to ensure adequate recovery from cataract surgery and/or recovery

Co-managed Post-operative Care 13

from complications. Center managed patients were more likely to have diabetes mellitus, diabetic retinopathy, or glaucoma. The data collected did not include the degree of severity of pre-existing ocular conditions and we suspect that individuals with more severe conditions are those managed by the center.

The visual acuity outcomes found in this study are comparable to those reported in previously published cataract surgery studies [4-131. Although most of these studies provide estimates of post-operative visual improvement after inpatient cataract surgery, involve sample sizes of less than 400 patients, and include a variety of different cataract removal and lens implantation techniques, they represent the only data available for comparison. In published studies, visual acuity improvements, defined using a standard of 20/40 or better, were experienced by 42-98% of eyes depending on the presence or absence of pre-existing medical and ocular conditions [&I 31. Most previous studies 20/40 or better visual acuity outcomes in 81-96% of procedures.

Patients receiving co-managed post-operative care experienced vision outcomes comparable to those patients reported in other large studies of cataract surgery. For example, the Food and Drug Administration (FDA) CORE study found that 87% of 3995 eyes having posterior chamber IOL achieved vision outcomes of 20/40 or better [7-9] cotnpared with 86% of co- managed eyes in the present study. In cases without pre-existing ocular conditions, 93% of eyes achieved 20140 or better vision in this study compared to 98% in the FDA study. In addition, the co-managed patients were low risk and therefore were expected to have better vision outcomes and fewer complications. The FDA and the current study are not directly comparable because of differences in method- ology, follow-up procedures and vision measurements.

An important concern related to co-management is whether optometrists are able to detect post-operative complications of cataract surgery. Failure to identify and treat complications may result in vision loss, blindness, and patient pain and discomfort. Twenty-eight percent of the complications occurring in this study were identified and treated by ophthalmologists before the patient was referred to an outside optometrist. Seventy-six percent of the remaining complications were detected by either center or outside optometrists during follow-up evalu-

ations. The overall accuracy of outside optometrist detection of complications, using physician diagnosis as the standard, was 95.9%, with a 59% sensitivity and 99.6% specificity. However, 41% of post-operative complications were identified during center visits following at least one patient visit to an outside optometrist. It is difficult to determine, using the available data, whether problems were present in these cases during the optometrist visit or whether they developed between the optometrist visit and the visit to the center. Another alternative expla- nation is that the patient contacted the optometrist by telephone and then was returned to the ophthalmologist for evaluation. The present findings suggest that optometrists are able to detect some post-operative problems although there is the possibility that some complications may be missed. Additional study is needed to examine this issue in greater detail.

Post-operative complication rates found in the present study were also comparable to complication rates reported in previous [4-9, 11, 131. However, other studies may include different definitions for the complications and often use different methods of data collection. In this study any of the listed complications occurring within 90 days following cataract surgery were included as complications regardless of its persistence. Many other studies, however, do not include short-term conditions, or conditions im- mediately following surgery as complications. Thus, in comparison with other studies, the complication rates may be overestimated. For example, cornea1 edema is a common short term post-operative condition and often is not included as a complication unless it persists 4 weeks after surgery [5]. It should be noted that the total complication rates for these outpatient surgical centers are slightly higher for combined center-managed and co-managed cases (8.1 vs 7.3%).

Co-managed post-operative care following cataract surgery can be successfully organized, coordinated, and delivered. Interviews with ophthalmologist and optometrists participating in co-managed care indicate that with coordi- nation and good communication procedures, co-managed post-operative care works well for the majority of cataract surgery patients. How- ever, there is the potential for loss to follow-up and patient confusion regarding which provider to contact if a complication develops. Key advantages for patients include improved access to and continuity of vision care, especially for


patients living in rural areas, reduced burden on family and friends, and increased compliance with follow-up vision services. Many of the patients served by the eye centers came from rural areas and had to travel over 40 miles to the center for surgery. Co-managed care relieves the traveling burden for these patients and their families and may increase compliance with follow-up care. Patients may be more likely to call or visit their optometrist if a problem develops and, therefore, complications may be identified and treated more quickly.

The study findings suggest that patients receiving post-operative care delivered by eye center providers and optometrists located outside of the center have vision outcomes and complication rates that are comparable to those reported in the medical literature. These finding were expected since most co-managed patients were low risk and thus were expected to have successful vision outcomes and low complication rates. The OTA report on co-managed care implied that optometrists, because of differences in training compared with ophthalmologists, might not deliver acceptable post- operative care following cataract surgery [ 181. The optometrists had an accuracy rate of 95.9%, however, 41% of complications were diagnosed by center physicians or optometrists after co-management by an outside optometrist. Although the reason for this discrepancy in detection of complications cannot be resolved by these data, it is possible that some complications were missed by optometrists. Prospective research is needed to determine whether optometrists have sufficient skills to detect most if not all serious complications that might occur following cataract surgery. The findings of this study need to be confirmed using prospective experimental or epidemiologic research design with systematic assessment of visual acuity and surveillance of post-operative complications.

Acknowledgement-This research was supported in part by a grant from the American Optometric Association.

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