Archana Bhan

Role of intraocular pressure measurement on the day of phacoemulsification cataract surgery

Purpose: To determine whether measurement of intraocular pressure (IOP) preoperatively or in the early postoperative period is an accurate predictor of raised IOP 24 hours after cataract surgery. Setting: Department of Ophthalmology, Queens Medical Centre, Nottingham, United Kingdom. Methods: This prospective study comprised 101 eyes of 101 patients having phacoemulsification cataract surgery. The IOP was measured by Goldmann applanation tonometry preoperatively and 2 to 3 hours, 6 to 8 hours, and 22 to 24 hours postoperatively. The relationship between the same‐day and next‐day IOP readings was examined. Results: One hundred patients completed the study. The IOP at 22 to 24 hours was significantly correlated with the IOP preoperatively (correlation coefficient [r] 0.54; 95% confidence interval [CI], 0.38‐0.67) and at 6 to 8 hours (r = 0.56; 95% CI, 0.41‐0.68). In contrast, the IOP measurement at 2 to 3 hours correlated relatively poorly with the next‐day IOP (r = 0.33; 95% CI, 0.14‐0.49). Twelve patients had an IOP of 26 mm Hg or higher at 22 to 24 hours. The risk of this outcome increased significantly with higher IOP values preoperatively and, to a lesser extent, with a raised IOP at 6 to 8 hours. Glaucoma and ocular hypertension were associated with a 2.9‐fold increased risk (95% CI, 0.67‐12.8) of a next‐day IOP of 26 mm Hg or higher. Conclusions: Preoperative IOP or a diagnosis of glaucoma or ocular hypertension were significant risk factors for raised next‐day IOP after small‐incision phacoemulsification. It may be possible to select patients at greater risk of prolonged ocular hypertension before surgery for prophylactic IOP‐lowering treatment. This would minimize patient morbidity and reduce the number of patients requiring next‐day review, resulting in significant health economic savings.

Effect of diabetes mellitus and hyperglycemia on the proliferation of human Tenon's capsule fibroblasts: Implications for wound healing after glaucoma drainage surgery

Glaucoma drainage surgery in diabetic patients is associated with a relatively poor prognosis due to increased scarring at the site of surgery, secondary to increased proliferation of human Tenons capsule fibroblasts (hTCF). This is in marked contrast to diabetic wound healing at other sites, where it is generally impaired. The aim of this study was to determine why diabetics show an increased ocular scarring response in comparison to that found at other sites. Under normoglycemic conditions, hTCF isolated from diabetics showed a mean reduction in short‐term proliferation (95% CI) of 45 ± 12% compared with normal controls (p < 0.001). Under hyperglycemic conditions, proliferation of diabetic hTCF was reduced by 21 ± 11% (p < 0.01) compared with nondiabetic controls. When exposed to transforming growth factor‐β2 (1–10,000 pg/ml) and platelet‐derived growth factor‐BB (0.5–500 ng/ml) under both normo‐ and hyperglycemic conditions, there was a dose‐related increase in proliferation of both diabetic and nondiabetic controls. There was no significant difference in response to cytokine stimulation between the two groups at any of the cytokine concentrations used. Western blot analysis did not show any apparent difference in the expression of platelet‐derived growth factor receptor α, mitogen‐activated protein kinase/ERK2, or transforming growth factor‐β receptor II to account for the reduced proliferation of diabetic hTCF. These results suggest that hTCF behave in a manner similar to fibroblasts from other nonocular sites and that the increased proliferation and scarring response found in vivo may be secondary to the previously noted elevated cytokine concentrations in the aqueous and vitreous of diabetics.

Sensitivity and specificity of a new scoring system for diabetic macular oedema detection using a confocal laser imaging system

AIM To assess the use of the Heidelberg retina tomograph (HRT) in screening for sight threatening diabetic macular oedema in a hospital diabetic clinic, using a new subjective analysis system (SCORE). METHODS 200 eyes of 100 consecutive diabetic patients attending a diabetologists clinic were studied, all eyes had an acuity of 6/9 or better. All patients underwent clinical examination by an ophthalmologist. Using the HRT, one good scan was obtained for each eye centred on the fovea. A System for Classification and Ordering of Retinal Edema (SCORE) was developed using subjective assessment of the colour map and the reflectivity image. The interobserver agreement of using this method to detect macular oedema was assessed by two observers (ophthalmic trainees) who were familiarised with SCORE by studying standard pictures of eyes not in the study. All scans were graded from 0–6 and test positive cases were defined as having a SCORE value of 0–2. The sensitivity of SCORE was assessed by pooling the data with an additional 88 scans of 88 eyes in order to reduce the confidence interval of the index. RESULTS 12 eyes in eight out of the 100 patients had macular oedema clinically. Three scans in three patients could not be analysed because of poor scan quality. In the additional group of scans 76 out of 88 eyes had macular oedema clinically. The scoring system had a specificity of 99% (95% CI 96–100) and sensitivity of 67% (95% CI 57–76). The predictive value of a negative test was 87% (95% CI 82–99), and that of a positive test was 95% (95% CI 86–99). The mean difference of the SCORE value between two observers was –0.2 (95% CI –0.5 to +0.07). CONCLUSIONS These data suggest that SCORE is potentially useful for detecting diabetic macular oedema in hospital diabetic patients.

Repeatability of ocular blood flow pneumotonometry

PURPOSE To establish the repeatability of ocular blood flow (OBF) pneumotonometry and its agreement with Goldmann tonometry. DESIGN Instrument evaluation study. PARTICIPANTS Ten female healthcare professionals. METHODS Intraocular pressure (IOP) was measured by one experienced ophthalmologist in both eyes of 10 healthy female subjects on 10 different occasions at the same time of day. The two methods were performed by alternate allocation, and laterality was chosen by random order. Repeatability coefficients and agreement plots were calculated by using the Bland-Altman method. MAIN OUTCOME MEASURES Intraocular pressure repeatability coefficients. RESULTS Mean IOPs were 15.6 mmHg (right) and 15.1 mmHg (left) by OBF pneumotonometry and 12.6 mmHg (right) and 12.4 mmHg (left) by Goldmann tonometry (P < 0.001). The repeatability coefficients were 7.06 (right) and 7.66 (left) for the OBF pneumotonometer and 4.81 (right) and 3.87 (left) for the Goldmann tonometer. With regard to agreement, the OBF pneumotonometer read significantly higher than did the Goldmann tonometer. The mean bias for the right eye was 2.92 (95% limits of agreement, -4.37 to 10.20), and for the left eye it was 2.68 (95% limits of agreement, -3.93 to 9.28). CONCLUSIONS In our group of healthy females, the repeatability of the OBF pneumotonometer was worse than that of the Goldmann tonometer. This casts doubt on the value of the OBF pneumotonometer as a tool for measuring IOP. The agreement plots indicate that the OBF pneumotonometer may produce significant numbers of false-positive results in screening programs.