Pseudophakic macular edema and oral acetazolamide: an optical coherence tomography measurable, dose-related response.

PURPOSE: Although uncommon after phacoemulsification surgery, cystoid macular edema (CME) is an important cause of postoperative reduction of vision after cataract surgery. To demonstrate an optical coherence tomography (OCT) measurable, dose-related response to orally administered acetazolamide in a patient presenting with pseudophakic CME. METHODS: A 76-year-old woman with reduced vision in right eye due to cataract had uneventful phacoemulsification. Surgery was complicated by early onset endophthalmitis that was treated with intravitreal antibiotics with good visual recovery. At 6 months follow-up, she presented with further reduction of vision (0.5 LogMAR) due to CME and a central foveal thickness (CFT) of 587 microm. RESULTS: Acetazolamide treatment was started in combination with topical ketorolac. At a daily dose of 500 mg, CFT and visual acuity were 262 microm and 0.34 LogMAR, respectively. Dose reduction of acetazolamide to 250 mg/day was associated with worsening of the CFT to 335 microm. CFT was subsequently measured at 230 microm on increasing the acetazolamide dose to 500 mg/day and measured 353 microm when acetazolamide dose was halved. CFT was 478 microm when acetazolamide was ceased.CONCLUSIONS. In this report, the authors have shown a dose-related response of pseudophakic CME to oral acetazolamide. This would suggest that the clinical response to oral acetazolamide may be titrated to the extent of CME and monitored by OCT.

High resolution imaging of fluorescein patterns in RCS rat retinae and their direct correlation with histology.

To assess the progressive changes in the retinal vascular bed of dystrophic and non-dystrophic Royal College of Surgeons (RCS) rats, retinae, were visualised correlating in vivo fundus fluorescein angiography (FA) with histology. FA was performed in rats aged 5 weeks to 2 years, using a Zeiss confocal scanning laser ophthalmoscope (cSLO). After the final imaging session, a subset of retinae were prepared for flat-mount histology and the vascular bed was visualised using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) staining. While non-dystrophic rat retinae showed no substantive changes in vascular patterns with age and no demonstrable fluorescein leakage up to at least 1 year, dystrophic rat retinae showed abnormal vascular formations, demonstrable on FA and NADPH-d staining, which could be correlated in single retinae. Hyperfluorescent spots and late angiographic leakage were evident beginning at 10 weeks and progressed in severity with time: they were coincident in distribution with abnormal histological vascular complexes. The ability to monitor the same retina serially makes this approach a valuable tool for studying the dynamics of vascular change in the diseased retina, not only during the course of degeneration but also when assessing efficacy of potential therapeutic approaches.

Vitrectomy and radial optic neurotomy for central retinal vein occlusion: effects on visual acuity and macular anatomy.

BACKGROUND: Central retinal vein occlusion (CRVO) is a common retinal vascular disorder and a leading cause of visual loss. It is thought to arise from vascular obstruction at the level of the lamina cribrosa. The purpose of the study reported here was to evaluate the potential benefit of radial optic neurotomy (RON) and determine its effect on foveal thickness and macular volume in patients with CRVO. METHODS: We conducted a prospective pilot study of ten patients with CRVO. Visual acuity (VA) score measured with the Early Treatment Diabetic Retinopathy Study chart and the corresponding Snellen equivalent were assessed before and 6 months after surgery. Colour fundus photography, fluorescein angiography (FA) and optical coherence tomography (OCT) were carried out before and at 2, 6, 12 and 24 weeks after surgery. Foveal thickness and macular volumes were assessed using OCT. RESULTS: Visible reperfusion was observed in four of the ten patients at the time of surgery. VA score improved in eight of the ten patients from a median score of 11.50 (range 0-68) to a median score of 35.00 (range 3-79). Macular volumes decreased in six of seven patients from a median of 4.99 mm3 (range 2.68-6.77) to a median of 3.11 mm3 (range 1.11-5.02). Foveal thickness decreased in six of seven patients from a median of 596.50 microm (range 338.50-745.50) to a median of 330.50 microm (range 118-634.50). Six of ten patients developed a chorioretinal venous anastomosis. Macular oedema on OCT persisted in six of ten patients. CONCLUSIONS: We observed an improvement in VA score and a corresponding reduction in foveal thickness and macular volume following RON, but macular oedema persisted in 60% of patients. Whilst optimisation of patient selection criteria remains a challenge, this pilot study suggests that RON has a beneficial effect on VA in patients presenting with CRVO.

Macular microholes: pathogenesis and natural history.

AIMS: To study the natural history and evaluate optical coherence tomography (OCT) and the retinal thickness analyser (RTA) in patients with macular microholes. METHODS: The medical records of 22 patients with a well demarcated red intraretinal foveal or juxtafoveal defect were reviewed. Fluorescein angiography (FA), RTA, and OCT were performed. The main outcome measures were visual acuity (VA), and OCT and RTA characteristics of microholes. Long term follow up was available in 13 eyes of 12 patients. RESULTS: The patients had a mean age of 50 years and a mean refractive error of -0.93 dioptres. The presenting symptom was a central scotoma in 14 eyes and metamorphopsia in eight eyes. All patients had a corrected VA ranging from 20/16 to 20/125, with 20 out of 24 eyes (83%) having a VA > or =20/40. Symptoms remained stable or improved in 16 out of 22 patients (72%). OCT 2 findings were normal but an abnormality of the outer retina and/or a defect of the retinal pigment epithelium (RPE) were demonstrated on OCT 3 in 15 of 18 eyes (83%). The RTA topographic map demonstrated a defect at the site of the microhole in two out of 12 eyes. CONCLUSION: Although biomicroscopic examination suggested an inner foveal defect, the OCT 3 scans demonstrated a localised abnormality of the outer retina and/or RPE which could not be resolved using OCT 2. Macular microholes have a favourable long term prognosis with stable VA. Bilateral involvement is uncommon.

Successful treatment of varicella zoster virus retinitis with aggressive intravitreal and systemic antiviral therapy.

AIMS: To describe the successful treatment of varicella zoster virus retinitis (VZVR) using intravenous cidofovir as part of an aggressive management strategy. CASE REPORTS: Two patients with bilateral VZVR were treated with a combination of intravenous cidofovir and ganciclovir with adjuvant intravitreal foscarnet or ganciclovir. Both patients maintained good vision in the less severely affected eye. Retinal detachment did not occur in either patient. CONCLUSIONS: VZVR should be treated aggressively with a combination of intravenous and intravitreal therapy to improve visual prognosis. Intravenous cidofovir, in the absence of contra-indications, should be considered as part of this aggressive therapeutic approach, especially in patients with AIDS in whom the prognosis is particularly poor.

CMVR diagnoses and progression of CD4 cell counts and HIV viral load measurements in HIV patients on HAART.

AIM: To assess the impact of highly active antiretroviral therapy (HAART) on the prevalence and progression of CMV retinitis (CMVR) among AIDS patients with baseline CD4 cell counts <100 cells x 10(6)/l. METHODS: A longitudinal cohort study of 1292 patients. CD4 cell counts and HIV viral load measurements were obtained before commencing therapy, at 3 months, 1 year, 2 years, and at last follow up. The CMVR prevalence rate was measured for the subgroup with baseline CD4 cell counts <100 cells x 10(6)/l. CMVR adverse event (AE) rates per 100 person days at risk were calculated for the subgroup with CMVR and baseline CD4 cell counts <100 cells x 10(6)/l. RESULTS: 1292 patients were started on HAART. 8% of patients had CD4 counts <50 cells x 10(6)/l and 40% had detectable HIV viral load at last follow up. The prevalence of CMVR for the subgroup with baseline CD4 <100 cells x 10(6)/l was 10%. For those with baseline CD4 <100 cells x 10(6)/l, the mean CMVR AE rate was greatest during the first 6 months of follow up after HAART commencement (p <0.003). The mean AE rate per 100 person days at risk was 0.36 (95% CI 0.167 to 0.551) before starting HAART, and 0.14 (95% CI 0.085 to 0.199) after starting HAART (p = 0.03). CONCLUSIONS: HAART significantly prolongs the disease-free intervals in patients with pre-existing disease but recurrences persist within the first 6 months of starting therapy. AE were absent beyond 18 months of follow up in all patients including those with persistently low CD4 counts and detectable HIV viral load indicating clinical immunorestoration. New methods for monitoring the response to therapy are needed to identify those at risk.

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 diabetologist's 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 familiarized 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.

Assessment of the Heidelberg Retina Tomograph in the detection of sight-threatening diabetic maculopathy.

PURPOSE: To assess the potential role of the Heidelberg Retina Tomograph (HRT) in screening for sight-threatening macular oedema in diabetes. METHODS: One hundred and thirty-one eyes of 81 consecutive diabetic patients who fitted the inclusion criteria were included in the study. On HRT, the volume above the reference plane bound within a 2 mm diameter circle centred at the fovea was measured. The volumetric indices were compared with the mean measurement index in a group of 20 age-matched controls (mean score = 1, mean +2 SD score = 1.8). We also assessed the sensitivity of the subjective analysis of the intensity image and the addition of the three-dimensional map to the intensity image for detecting macular oedema and clinically significant macular oedema (CSMO). RESULTS: One hundred and twelve eyes of 71 patients had a corrected Snellen visual acuity of 6/9 or better. When considering eyes with 6/9 or better vision only, the system's sensitivity for detecting CSMO was 58.33% 'per eye' examined, and 81.82% 'per patient' examined using a cut-off volumetric index of 1.8. In our study eyes with 6/9 or better vision, we found a 21% prevalence of CSMO. The predictive values of a positive test were 38.89% and 45% (cut-off score 1.8, 'per eye' and 'per patient' respectively) for CSMO. The predictive values of a negative test were 86.84% and 90.48% (cut-off score 1.8, 'per eye' and 'per patient' respectively) for CSMO. CONCLUSIONS: The volumetric assessment of diabetic maculopathy by HRT is a potentially useful method for screening eyes at risk. A larger group of patients with a greater number of eyes with minimal or no maculopathy is required to establish the specificity of this technique.

Topographic and keratometric astigmatism up to 1 year following small flap trabeculectomy (microtrabeculectomy).

AIM: To determine the induced corneal astigmatism by measuring the changes in manual keratometry and computerised corneal videokeratoscopy up to 1 year following small flap trabeculectomy (microtrabeculectomy). METHOD: A prospective study of a case series of small flap trabeculectomy procedures performed at the 90 degree meridian on 16 eyes of 16 patients, all followed to 1 year postoperatively. Changes in manual keratometry and computerised videokeratoscopy (Eyesys) readings were analysed by vector analysis and vector decomposition techniques. RESULTS: By vector analysis, the mean surgically induced refractive change (SIRC) cylinder power vectors induced at 1, 3, 6, and 12 months as measured by manual keratometry were 0.68, 0.38, 0.52, and 0.55 dioptres, and by keratography 0.75, 0.66, 0.59, and 0.64 dioptres. Vector decomposition on the induced vector cylinders on manual keratometry resulted in a "with the rule" mean vector of 0.52 and 0.22 dioptres at 1 and 3 months and an "against the rule" mean vector of 0.16 and 0.16 dioptres at the same time points (p=0.03 and 0.28 respectively). Vector decomposition at 6 and 12 months revealed no significant with the rule changes induced. Similar analysis on the videokeratoscopy results revealed significant induced with the rule astigmatism until 3 months, but not at 6 and 12 months postoperatively. CONCLUSION: Small flap trabeculectomy (microtrabeculectomy) produces smaller changes in corneal curvature that resolve sooner than previous reports of larger flap techniques.

Reproducibility of volumetric macular measurements in diabetic patients with the Heidelberg Retina Tomograph.

AIMS: To quantify diabetic macular edema by confocal scanning laser ophthalmoscopy and assess its usefulness by determining the reproducibility of topographic measurements at the macula. METHODS: The volumes above reference plane bound by a 2 mm diameter circle centred on the fovea were measured by two observers. The reference plane was adjusted to the lowest point of the height variation of the contour line. The reproducibility of this technique was assessed in 20 eyes of 20 diabetic patients of which 8 eyes had macular edema. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times. RESULTS: For all diabetic eyes, the intra scan coefficients of variability measured 14.71% to 21.21%, the inter scan coefficient of variability was 30.46%. The average standard deviations were 0.053 mm3 for one examination per scan, 0.047 mm3 for two examinations per scan and 0.044 mm3 for three examinations per scan. Linear regression demonstrated an increase in standard deviation with greater volumetric measurements (p < 0.001). We found good correlation (r = 0.959, p < 0.001) and strong agreement between the two observer's findings for all 20 eyes. For the 8 eyes with macular edema, the coefficients of variability were similar to those calculated for all 20 eyes. The average SD for one examination per scan were 0.078 mm3, 0.069 mm3 for two examinations per scan and 0.062 mm3 for three examinations per scan. We found good correlation (r = 0.945, p < 0.001) and strong agreement between the two observer's findings in eyes with edema. CONCLUSION: The reproducibility of this technique has been demonstrated in diabetic eyes. This may have useful clinical applications for the quantification of diabetic macular edema and monitoring of laser therapy.

Reproducibility of volumetric measurements of normal maculae with the Heidelberg retina tomograph.

AIMS: The Heidelberg retina tomograph (HRT) is a scanning laser ophthalmoscope with confocal optics. The reproducibility of the optic nerve head topography is accurate and reliable. The authors describe a new technique for the assessment of macular thickening by volumetric quantification and present the results of its reproducibility in normal subjects. METHODS: Topographic images of the macula, centred on the fovea were obtained in one eye of 44 normal subjects. The volumes above the reference plane bound by a 1 mm, 2 mm, and 3 mm diameter circle were measured. The reference plane was adjusted to the lowest point of the height variation of the contour line at each examination. The reproducibility of repeated measurements within a 2 mm diameter circle was assessed in 20 eyes selected at random. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times on three separate days. RESULTS: The intrascan coefficients of variability measured 7.12-9.57%. The 95% confidence interval for the geometric mean ratio of single volume measurements was 0.92 to 1.24 for scans 1 and 2, 0.89 to 1.17 for scans 1 and 3, and 0.81 to 1.12 for scans 2 and 3. When the mean of three measurements of one scan were compared with the mean of three measurements of a second scan, the 95% confidence interval for their geometric mean ratio was 0.89 to 1.20 for scans 1 and 2, 0.89 to 1.16 for scans 1 and 3, and 0.84 to 1.13 for scans 2 and 3. The average standard deviation (SD) for one measurement per scan was 0.02 mm3, and 0.019 mm3 for two or three measurements per scan. Linear regression demonstrated a significant increase in SD as volumetric measurements increased (p = 0.003). Age did not significantly affect the SD of volumetric measurements (p = 0.797). The authors found no significant differences in volumetric measurements across all ages for all three circles (p = 0.314, p = 0.471, p = 0.267). CONCLUSION: Good reproducibility for volumetric measurements at the macula was found with the HRT using the above technique in normal subjects. This method may be extremely useful for the identification and quantification of diabetic macular oedema and for monitoring the effects of argon laser photocoagulation.

Volumetric analysis of early macular edema with the Heidelberg Retina Tomograph in diabetic retinopathy.

OBJECTIVE: This study describes a new method for the quantification of diabetic macular edema by volumetric analysis with the Heidelberg Retina Tomograph (HRT) scanning laser ophthalmoscope. DESIGN: Topographic images of the macula were obtained in 25 consecutive patients who fitted the inclusion criteria. Twenty age-matched control subjects were randomly selected for a similar examination. PARTICIPANTS: Twenty normal control eyes and 32 eyes of 25 patients with diabetes mellitus were studied. INTERVENTION: Patients with diabetes were examined by HRT and slit-lamp biomicroscopy with a contact lens. On HRT, the volumes above reference plane bound by three consecutive circles centered at the fovea (diameter, 1, 2, and 3 mm) were measured. Measurements were repeated three times in a masked fashion, and the mean measurements were used for the analysis. MAIN OUTCOME MEASURES: Visual acuity, macular edema, and volume above reference plane were measured. RESULTS: There were 19 diabetic eyes with clinical macular edema (deemed positives) and 13 without edema (deemed negatives). Diabetic eyes with macular edema had statistically greater volumes above reference plane than did diabetic eyes without edema (P < 0.001) and greater than the control eyes (P < 0.001) for all three circles. There was no statistically significant difference between volumes measured in eyes without macular edema and control eyes (P = 0.42 for the 1-mm diameter circle; P = 0.72 for the 2-mm diameter circle; and P = 0.19 for the 3-mm diameter circle). For the two smallest circles only, the sensitivity of the HRT was 78.94%, and the specificity was 84.61%. None of the patients missed on the two smallest circles would have been positively identified on the 3-mm diameter circle. CONCLUSION: The HRT can detect and quantify macular edema in diabetes by volumetric analysis with the method the authors have described. It is sufficient to measure the volumes above reference plane of two circles centered on the fovea and measuring 1 and 2 mm in diameter because the 3-mm diameter circle does not increase the system's sensitivity.

Medium to long-term intraocular pressure control following small flap trabeculectomy (microtrabeculectomy) in relatively low risk eyes.

AIM: To determine the long-term efficacy of small flap trabeculectomy (microtrabeculectomy) in terms of intraocular pressure (IOP) control in relatively low risk eyes. METHOD: A review of a case series of small flap trabeculectomy procedures performed on 36 eyes from 36 patients with a minimum follow up of 24 months (mean 50.8). RESULTS: The mean (SD) intraocular pressures at presentation and preoperatively were 33.7 (7.5) and 24.6 (4.5) mm Hg. At 6 months, 1, 2, 3, 4, 5, and 6 years the mean (n, SD) IOPs (mm Hg) of those eyes followed to each time point were 11.9 (36, 4.6), 12.6 (36, 4.7), 13.2 (36, 4.6), 13.7 (29, 4.1), 13.2 (22, 4.0), 12.7 (15, 4.8), and 12.3 (8, 4.7) respectively. There was no significant difference in IOP levels at any of the analysis points by one way ANOVA. Kaplan-Meier analysis revealed survival rates of 80% at 4 years and 75% at 5 years when any postoperative IOP > 20 mm Hg is considered a failure, and 50% at 6 years when any IOP > 15 mm Hg is classed as a failure. CONCLUSION: Small flap trabeculectomy (microtrabeculectomy) is effective at reducing IOP in low risk glaucoma eyes with IOP control similar to previous reports of filtering surgery utilising larger scleral trapdoors.

Capsulorhexis phymosis following uncomplicated phacoemulsification surgery.

PURPOSE: The aim of the study was to assess and compare the degree of capsulorhexis phymosis following uncomplicated phacoemulsification cataract surgery in polymethylmethacrylate (PMMA) and silicone lens implants. METHOD: Sixty-four patients were evaluated 1 day, 6 weeks and 6 months following phacoemulsification cataract extraction. The anterior capsular diameters were measured with the illuminated beam of the slit lamp at 45 degrees and 135 degrees and the surface area of the opening calculated. We have measured and compared the change in the capsulorhexis size for both lens types and assessed its statistical significance with a paired Student's t-test. RESULTS: A statistically significant contraction of the capsulorhexis was noted in all patients within the first 6 weeks (p < 0.001). Capsular contraction continued between 6 weeks and 6 months post-operatively but to a lesser extent (p < 0.05). The difference in the degree of phymosis between the first period (1 day to 6 weeks) and the second (6 weeks to 6 months) was statistically highly significant for all patients (p < 0.001). The capsular areas for the silicone lens implants were significantly smaller than for the PMMA implants at 6 weeks and 6 months. None of our patients had a clinically significant capsular contracture requiring Nd:YAG laser capsulotomy. CONCLUSION: Anterior capsular contraction is commonly observed following capsulorhexis in phacoemulsification surgery. This study demonstrates that the maximum rate of contraction occurs in the first 6 weeks following surgery and is more pronounced with silicone lens implants.