Shaheeda Mohamed

Analysis of bleb morphology after trabeculectomy with Visante anterior segment optical coherence tomography

Background: To describe the use of anterior segment optical coherence tomography (OCT) in imaging intrableb morphology after trabeculectomy. Methods: 14 post-trabeculectomy eyes from 11 primary open angle glaucoma and 3 primary angle closure glaucoma subjects were studied. The blebs were classified with reference to slit lamp morphology and bleb function. They included diffuse filtering (n = 7), cystic (n = 2), encapsulated (n = 2) and flattened (n = 3) bleb types. One eye in each patient was imaged with the Visante anterior segment OCT. A vertical scan line of 10 mm consisting of 512 A-scans was positioned at the centre of the bleb. The images were then analysed by built-in software. Intrableb morphologies and structures, including bleb wall thickness, subconjunctival fluid collections, suprascleral fluid space, scleral flap thickness, intrableb intensity (low, medium or high) and the route under the scleral flap were characterised and measured. Results: Diffuse filtering blebs were found by subconjunctival fluid collections. Suprascleral fluid space and the route under the scleral flap were identified in four of the seven cases. Cystic blebs were composed of a large hyporeflective space with multiloculated fluid collections covered by a thin layer of conjunctiva. Encapsulated blebs had a thick bleb wall with high reflectivity and an enclosed fluid filled space. Flattened blebs demonstrated high scleral reflectivity and no bleb elevation. Conclusions: Visante anterior segment OCT can be used for bleb imaging. The different patterns of intrableb morphology identified by OCT were related to slit lamp appearance and bleb function. This information may be useful to study the different surgical outcomes and the process of wound healing in trabeculectomised eyes.

Efficacy of 1.25 MG versus 2.5 MG intravitreal bevacizumab for diabetic macular edema: six-month results of a randomized controlled trial.

Purpose: To evaluate the efficacy of intravitreal injections of two different dosages of bevacizumab (Avastin) for treating diffuse diabetic macular edema. Methods: Fifty-two eyes of 52 patients with diabetic macular edema were randomized to receive three monthly intravitreal injections of 1.25 mg or 2.5 mg bevacizumab. Patients were observed for 6 months and optical coherence tomography central foveal thickness, logMAR best-corrected visual acuity (BCVA), and adverse events were assessed. Results: Forty-eight eyes of 48 patients completed the 6-month follow-up and were analyzed. Significant mean central foveal thickness reductions were observed in both groups at all follow-up visits (P < 0.013). Significant improvements between baseline and 6-month mean logMAR BCVAs were seen, with the mean logMAR BCVA improved from 0.63 to 0.52 in the 1.25 mg group and 0.60 to 0.47 in the 2.5 mg group. No significant difference in BCVA was observed between the two groups at any time point (P > 0.56). Subgroup analysis showed that intravitreal bevacizumab seemed to be more effective in eyes without any previous diabetic macular edema treatment. Conclusions: Three monthly intravitreal bevacizumab injections resulted in significant reduction in central foveal thickness and improvements in BCVA in diabetic macular edema patients. Both 1.25 mg and 2.5 mg seemed to have similar treatment efficacy.

Phacoemulsification with intravitreal triamcinolone in patients with cataract and coexisting diabetic macular oedema: a 6-month prospective pilot study

AimsTo assess the safety and efficacy of phacoemulsification with intravitreal triamcinolone (ivTA) injection in diabetics with cataract and clinically significant macular oedema (CSMO).MethodsA total of 19 eyes of 15 consecutive diabetic patients with cataract and CSMO were prospectively recruited. Patients underwent phacoemulsification and intraocular lens implantation with 4 mg ivTA injection at completion of surgery. Patients were followed up on day 1, then weekly for 1 month, and thereafter monthly until 6 months postoperatively. Best corrected visual acuity (BCVA), central macular thickness (CMT) measured by optical coherence tomography, and adverse events were recorded.ResultsIn total, 17 eyes completed 6 months of follow-up. In all, 58.8% showed improvement in BCVA of ⩾2 lines, with statistically significant improvement in mean Snellen BCVA of 2.4 lines at 6 months. The peak BCVA was achieved at 4 months. The mean CMT decreased from a baseline of 449 μm to a minimum of 321±148 μm (28.5% reduction) achieved at 2 months, with statistically significant reduction at all postoperative time intervals until 6 months. Of 17 eyes, 4 (23.5%) developed transiently elevated intraocular pressure that normalised by 6 months in all but one patient. No injection- or surgery-related complications were encountered.ConclusionsPhacoemulsification with concurrent 4 mg ivTA injection appears to be a safe option for managing diabetics with cataract and CSMO. However, large-scaled randomised controlled trials are necessary for delineating the relative contributions of cataract removal and CMT reduction to visual improvement. Moreover, the transient effect on CMT may warrant further studies to determine optimal timing and dosage of further ivTA injections.

25-Gauge transconjunctival sutureless vitrectomy system in the surgical management of children with posterior capsular opacification

Purpose:  To evaluate the safety and efficacy of the 25‐gauge transconjunctival sutureless vitrectomy (TSV) system in the surgical management of posterior capsular opacification (PCO) in pseudophakic children.

Improvement of Visual Acuity in Eyes with Diabetic Macular Edema after Treatment with Pars plana Vitrectomy

Background: Diabetic macular edema (DME) is the leading cause of severe visual loss in patients with diabetic retinopathy. This is so despite the fact that argon laser photocoagulation of the macula (M-ALC) has been shown to be beneficial. Recently, it has been suggested that pars plana vitrectomy (PPV) can lead to the resolution of DME and stop the deterioration of central visual acuity. Purpose: To explore the potential benefit of PPV for the treatment of DME. Patients and Methods: PPV was carried out in 30 eyes of 21 consecutive patients (median age 71 years, range 61–88 years) with type II diabetes mellitus suffering from DME. 23 eyes had non-proliferative diabetic retinopathy (NPDR) and 7 eyes had proliferative diabetic retinopathy (PDR) in addition to DME. Posterior vitreous detachment had to be carried out in all cases. If epiretinal membranes were present (23 eyes), they were removed. In 13 eyes (initially 11 eyes) the internal limiting membrane (ILM) was also removed. Prior to PPV 8 eyes had received M-ALC. Three eyes had M-ALC after PPV. One eye developed a retinal detachment 6 weeks after PPV and was excluded form the analysis. After an initial treatment failure two eyes underwent repeat PPV with peeling of the ILM. Both eyes of another patient had 2 repeat PPVs because of recurrent vitreous hemorrhage. Median follow-up was 16 months (range 1–62 months). Results: Following PPV the macula flattened or became attached in 20/27 (74%) eyes. 15/18 (83%) eyes showed reduction or disapearance of leakage during fluorescein-angiography. Central visual acuity increased by two to six lines in 15/27 (56%) for the whole group at 6 months after PPV. For the subgroup (18 eyes) for which the evolution of visual acuity prior to PPV could be documented mean and median visual acuity had decreased markedly from 0.26 ± 0.19 resp. 0.2 (range 0.03–0.6) to 0.12 ± 0.09 resp. 0.1 (range 0.02–0.4) during the 12 months preceding PPV and increased to 0.28 ± 0.23 resp. 0.2 (range 0.03–0.8) during the 12 months following PPV. Conclusion: PPV almost always results in a reduction and often complete disappearance of DME as evidenced by ophthalmoscopy and fluorescein-angiography. Most importantly, central visual acuity often increases, sometimes to a very large extent with dramatic improvement in quality of life of the patients.

Decreasing efficacy of repeated intravitreal triamcinolone injections in diabetic macular oedema.

Background/aim: Intravitreal triamcinolone (IVTA) results in transient improvements in diabetic macular oedema (DMO), necessitating repeated injections. The authors report a case series of 10 eyes of 10 patients with DMO, who received a repeat injection of 4 mg IVTA, at least 26 weeks after the first injection of the same dose. Method: Pre-injection and at 2, 4, 9, and 17 weeks post-injection, best corrected visual acuity (BCVA) and central foveal thickness (CFT) on optical coherence tomography, after the first and repeat injections, were compared using paired t test. Side effects were monitored. Results: BCVA, CFT, intraocular pressure (IOP), and cataract scores were not significantly different before initial and repeat injections (given at 32.5 (SD 3.5) weeks after the first injection). Transient improvements of BCVA and CFT were achieved after both injections. However, after the repeat injection, the BCVA was significantly worse at all time points (p<0.05) and so were the best achieved CFT and the CFT at 4 weeks post-injection (p = 0.034 and 0.011 respectively), compared with the initial injection. Post-injection maximum IOPs and increase in cataract scores were not significantly different between the two injections. Conclusion: A repeat injection of 4 mg of IVTA may not be as effective as an initial injection for the treatment of DMO.

Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

Early microvascular damage in diabetes (e.g. capillary nonperfusion and ischemia) can now be assessed and quantified with optical coherence tomography-angiography (OCT-A). The morphology of vascular tissue is indeed affected by different factors; however, there is a paucity of data examining whether OCT-A metrics are influenced by ocular, systemic and demographic variables in subjects with diabetes. We conducted an observational cross-sectional study and included 434 eyes from 286 patients with diabetes. Foveal avascular zone (FAZ) area, FAZ circularity, total and parafoveal vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI) from the superficial capillary plexus OCT-angiogram were measured by a customized automated image analysis program. We found that diabetic retinopathy (DR) severity was associated with increased FAZ area, decreased FAZ circularity, lower VD, lower FD, and increased VDI. Enlarged FAZ area was correlated with shorter axial length and thinner central subfield macular thickness. Decreased FAZ circularity was correlated with a reduction in visual function. Decreased VD was correlated with thinner macular ganglion-cell inner plexiform layer. Increased VDI was correlated with higher fasting glucose level. We concluded that the effects of ocular and systemic factors in diabetics should be taken into consideration when assessing microvascular alterations via OCT-A.

Correction factor in Orbscan II in the assessment of corneal pachymetry.

Purpose: Comparison of corneal pachymetry assessment with ultrasound and Orbscan II using acoustic factor and subtraction methods. Methods: Ultrasound and Orbscan pachymetry for all patients with LASIK performed between July 2002 and May 2003 were retrospectively analyzed. Comparison between the 2 preoperative measurements was analyzed. Results: Using a custom acoustic factor of 0.93, there was no significant difference between the overall ultrasound and Orbscan pachymetry (P = 0.696). However, there was underestimation in thick corneas and overestimation in thin corneas. Using the subtraction method as the correcting technique, the magnitude of over- and underestimation was reduced. Conclusion: The current correction method by means of acoustic factor may result in error in assessing extremes of corneal thickness. Alternative approaches such as the subtraction method can be considered to achieve more accurate results.

Intravitreal dexamethasone for diabetic macular edema: a pilot study.

BACKGROUND AND OBJECTIVE To determine the response and safety profile of intravitreal dexamethasone in treating diabetic macular edema. PATIENTS AND METHODS In this prospective pilot study, 12 eyes of 12 patients with diabetic macular edema were randomized to receive a single injection of 0.4 mg (n = 6) or 0.8 mg (n = 6) of intravitreal dexamethasone. The outcome measures were changes in best-corrected visual acuity and central foveal thickness on optical coherence tomography. Side effects were monitored. RESULTS The 3-month results were reported. In both dosage groups, there were transient improvements in best-corrected visual acuity and central foveal thickness, but the changes were not significant at any time point (best-corrected visual acuity: P > or = 0.14; central foveal thickness: P > or = .08). No significant side effects were observed, except one eye developed a peak intraocular pressure of greater than 21 mm Hg. CONCLUSION A single injection of intravitreal dexamethasone (0.4 or 0.8 mg) did not have significant beneficial effects on diabetic macular edema within 3 months from injection in this small pilot study.

Advances of optical coherence tomography in myopia and pathologic myopia

The natural course of high-axial myopia is variable and the development of pathologic myopia is not fully understood. Advancements in optical coherence tomography (OCT) technology have revealed peculiar intraocular structures in highly myopic eyes and unprecedented pathologies that cause visual impairment. New OCT findings include posterior precortical vitreous pocket and precursor stages of posterior vitreous detachment; peripapillary intrachoroidal cavitation; morphological patterns of scleral inner curvature and dome-shaped macula. Swept source OCT is capable of imaging deeper layers in the posterior pole for investigation of optic nerve pits, stretched and thinned lamina cribrosa, elongated dural attachment at posterior scleral canal, and enlargement of retrobulbar subarachnoid spaces. This has therefore enabled further evaluation of various visual field defects in high myopia and the pathogenesis of glaucomatous optic neuropathy. OCT has many potential clinical uses in managing visual impairing conditions in pathologic myopia. Understanding how retinal nerve fibers are redistributed in axial elongation will allow the development of auto-segmentation software for diagnosis and monitoring progression of glaucoma. OCT is indispensable in the diagnosis of various conditions associated with myopic traction maculopathy and monitoring of post-surgical outcomes. In addition, OCT is commonly used in the multimodal imaging assessment of myopic choroidal neovascularization. Biometry and topography of the retinal layers and choroid will soon be validated for the classification of myopic maculopathy for utilization in epidemiological studies as well as clinical trials.