Harsha Laxmana Rao

Evaluation of central corneal thickness measurement with RTVue spectral domain optical coherence tomography in normal subjects.

Purpose: To determine (1) repeatability of central corneal thickness (CCT) measurements by spectral domain optical coherence tomography (RTVue; Optovue, Inc, Fremont, CA) and (2) agreement between CCT measurements by RTVue and those by ultrasonic pachymetry, Orbscan, and anterior segment optical coherence tomography (ASOCT). Methods: In a prospective observational study, 2 cohorts of normal subjects were recruited. In the first cohort (51 subjects), 5 measurements of CCT were obtained by RTVue during the same visit to determine the repeatability. In the second cohort (65 subjects), CCT measurements were obtained by RTVue, ultrasonic pachymetry, Orbscan, and ASOCT during the same visit to determine the agreement among these instruments. Repeatability was assessed by intraclass correlation coefficient (ICC), within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation. Agreement was assessed by ICC and Bland and Altman plots. Results: Repeatability of CCT measurements by RTVue as assessed by ICC, within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation was 0.99 (0.99-0.99), 2.2 (1.9-2.5), 4.2 μm (3.6-4.8), and 0.4% (0.3-0.5), respectively. The average CCT by RTVue (529 μm) was comparable to that by ultrasonic pachymetry (539 μm; P = 0.15), Orbscan (536 μm; P = 0.54), and ASOCT (526 μm; P = 0.77). The 95% limits of agreement on Bland and Altman plots ranged from 20 μm (between RTVue and ASOCT) to 33 μm (between RTVue and Orbscan). Conclusions: CCT measurements by RTVue have an excellent repeatability. Although CCT measurements by RTVue are comparable to that by ultrasonic pachymetry, Orbscan, and ASOCT, the difference between instruments can be significant depending on the clinical situation considered.

Effect of cataract extraction on Visual Field Index in glaucoma.

Purpose:To determine the effect of cataract on the Visual Field Index (VFI) in glaucoma patients. Methods:Reliable visual fields (VFs) of 53 patients (53 eyes) with primary glaucoma who underwent phacoemulsification either alone or combined with trabeculectomy were analyzed before and after surgery. All patients had VFs within a period of 15 months before and after surgery. VFI, mean deviation (MD), and pattern standard deviation (PSD) before surgery were compared with those after surgery. Results:Median (25th and 75th percentiles) MD after cataract surgery [−10.52 dB (range, −19.25 to −4.86 dB)] was significantly better (P=0.003) than that before surgery [−11.74 dB (range, −20.61 to −7.15 dB)]. Median PSD after surgery [4.76 dB (range, 2.48 to 9.83)] was worse (P=0.01) than that before surgery [3.50 dB (range, 1.93 to 8.20 dB)] when eyes with MD better than −20 dB were considered (41 eyes). VFI after surgery [80% (range, 44% to 94%)] was similar (P=0.92) to that before surgery [77% (range, 37% to 92%)]. MD improved while VFI remained unchanged in both nuclear sclerotic (n=41) and posterior subcapsular cataracts (n=12). Conclusions:MD and PSD were significantly affected, whereas VFI was not affected by cataract. VFI may be a more robust measure of VF damage than MD or PSD in glaucomatous eyes with coexisting cataracts.

Phacotrabeculectomy without mitomycin C in primary angle-closure and open-angle glaucoma.

PurposeTo compare the surgical outcomes of single site phacotrabeculectomy without mitomycin C (MMC) in primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG). MethodsWe retrospectively reviewed the records of all patients with a diagnosis of PACG and POAG, who underwent single site phacotrabeculectomy without MMC between January 2001 and December 2005 and had a minimum follow-up of 12 months. The primary outcome measure was cumulative success probability, defined as complete [intraocular pressure (IOP) ⩽21 mm Hg without antiglaucoma medications or additional surgery] and qualified (IOP <21 mm Hg with medications). Secondary outcome measures were reduction of IOP, the number of antiglaucoma medications at last follow–up, and complication rates. ResultsSeventy-one eyes of 63 PACG patients (mean age 61.2 y) and 72 eyes of 57 POAG patients (mean age 64.0 y) were analyzed. Mean duration of follow-up was 38.7 and 41.7 months in the PACG and POAG groups, respectively. Complete success in PACG (72.1%) was more than the POAG group (56.1%), but the difference was not statistically significant (P=0.06). Qualified success in the PACG and POAG group was 87.4% and 92.8%, respectively (P=0.43). IOP reduction was greater (P=0.03) in the PACG group and PACG group required fewer antiglaucoma medications postoperatively (P=0.03) for IOP control. ConclusionsSurvival probability of single site phacotrabeculectomy without MMC was not significantly different between the PACG and POAG groups. IOP reduction was greater and the need for antiglaucoma medications after surgery was lesser in the PACG group.

A Study of Prevalence and Risk Factors of Diabetic Retinopathy in Patients with Non-Arteritic Anterior Ischemic Optic Neuropathy (NA-AION)

Abstract Purpose: To estimate prevalence and risk factors for diabetic retinopathy (DR) in diabetic patients with Non-Arteritic Anterior Ischemic Retinopathy (NA-AION). Methods: This was a retrospective chart review of patients with diabetes diagnosed with NA-AION. Patients with clinical anomalies affecting the optic nerve, diabetic papillopathy, and features suggestive of arteritic AION (raised erythrocyte sedimentation rate/positive temporal artery biopsy) were excluded. Clinical diagrams, notes, and fundus photographs, if available, were evaluated for optic disc edema, optic disc atrophy, presence or absence of small discs, retinal vessel abnormalities, presence of DR, and the presence of sight-threatening DR (STDR). Results: A total of 153 eyes of 109 subjects were included in the study. 82 subjects (75.2%) were men. Mean age of the subjects was 55u2009±u20099 years. 58 subjects (53.7%) had hypertension and 21 (19.3%) were insulin-dependent. 80 subjects (52.3%) had a duration of diabetes of five years or greater. DR with NA-AION was seen in 46 eyes (30.1%, 95% CI: 22.7 to 37.4) and STDR with NA-AION was seen in 20 eyes (13.1%, 95% CI: 7.7 to 18.5). Logistic regression analysis revealed the duration of diabetes to be significantly associated with both the presence of DR (OR: 1.07, 95% CI: 1.01 to 1.14, pu2009=u20090.02) and STDR (OR 1.08, 95% CI: 1.02–1.15, pu2009=u20090.01). Conclusions: Prevalence of DR and STDR in eyes with NA-AION was 30.1% and 13.1%, respectively. Duration of diabetes was an important risk factor for both presence and severity of DR in subjects with NA-AION.

Glaucoma symptom scale: is it a reliable measure of symptoms in glaucoma patients?

Glaucoma is the leading cause of irreversible blindness worldwide after cataract and accounts for 10% of the worlds blind.1 Although patients with acute angle closure glaucoma are symptomatic, those with other forms of glaucoma (at least in the early stages) usually do not experience many symptoms, thereby, resulting in the disease often going unnoticed with possible progression. In some cases, patients with fluctuating levels of intraocular pressure may experience blurred vision and see haloes around lights. The Glaucoma Symptom Scale (GSS) was developed to assess ophthalmic symptoms experienced by patients with glaucoma.2 The GSS comprises 10 ocular symptoms, of which six are non-visual and four are visual. The non-visual symptoms include ‘burning/smarting/stinging’, ‘tearing’, ‘dryness’, ‘itching’, ‘soreness/tiredness’, and ‘feeling of something in the eye’. The visual symptoms include ‘blurry/dim vision’, ‘hard to see in daylight’, ‘hard to see in darkness’, and ‘halos around lights’. The GSS is unique in that it assesses symptoms as compared with visual functioning by other glaucoma-specific questionnaires. Like most questionnaires in ophthalmology, the GSS was also developed using traditional psychometric methods, that is, the classical test theory (CTT).3 The limitations of CTT have been well acknowledged. A major shortcoming of CTT pertains to its scoring assumptions: Likert or summary scoring in which the scores are calculated from …

Evidence-based approach to glaucoma management

Evidence-based medicine is an evolving new paradigm. With the advent of numerous new diagnostic techniques and therapeutic interventions, one needs to critically evaluate and validate them by appropriate methods before adopting them into day-to-day patient care. The concepts involved in the evaluation of diagnostic tests and therapy are discussed. For delivering the highest level of clinical care, evidence alone is not sufficient. Integrating individual clinical experience and patients’ perspectives with the best available external evidence is essential.

Optic nerve head parameters of high-definition optical coherence tomography and Heidelberg retina tomogram in perimetric and preperimetric glaucoma

Background: Heidelberg retina tomogram (HRT) and optical coherence tomography (OCT) are two widely used imaging modalities to evaluate the optic nerve head (ONH) in glaucoma. Purpose: To compare the ONH parameters of HRT3 and high-definition OCT (HD-OCT) and evaluate their diagnostic abilities in perimetric and preperimetric glaucoma. Design: Cross-sectional analysis. Methods: 35 control eyes (24 subjects), 21 preperimetric glaucoma eyes (15 patients), and 64 perimetric glaucoma eyes (44 patients) from the Longitudinal Glaucoma Evaluation Study underwent HRT3 and HD-OCT examinations. Statistical Analysis: Agreement between the ONH parameters of HRT and HD-OCT were assessed using Bland-Altman plots. Diagnostic abilities of ONH parameters were evaluated using area under the receiver operating characteristic curves (AUCs), sensitivity at fixed specificity, and likelihood ratios (LR). Results: Optic disc area, vertical cup to disc ratio, and cup volume with HD-OCT were larger than with HRT, while the rim area was smaller with HD-OCT (P < 0.001 for all comparisons). AUCs of all HD-OCT ONH parameters (0.90-0.97 in perimetric and 0.62-0.71 in preperimetric glaucoma) were comparable (P > 0.10) to the corresponding HRT ONH parameters (0.81-0.95 in perimetric and 0.55-0.72 in preperimetric glaucoma). LRs associated with diagnostic categorization of ONH parameters of both HD-OCT and HRT were associated with larger effects on posttest probability of perimetric compared to preperimetric glaucoma. Conclusions: ONH measurements of HD-OCT and HRT3 cannot be used interchangeably. Though the diagnostic abilities of ONH parameters of HD-OCT and HRT in glaucoma were comparable, the same were significantly lower in preperimetric compared to perimetric glaucoma.

LV Prasad Eye Institute Glaucoma Epidemiology and Molecular Genetic Study (LVPEI- GLEAMS). Report 1: Study Design and Research Methodology

Abstract Purpose: In the developing world, more than 90% of glaucoma is undetected due to the lack of appropriate screening methods. The LV Prasad Eye Institute Glaucoma Epidemiology and Molecular Genetic Study (LVPEI-GLEAMS) is a population-based study which aims to estimate the prevalence of, along with clinical, systemic and genetic risk factors for glaucoma in a rural population sampled from the state of Andhra Pradesh, India. The study aims to develop community screening strategies to diagnose glaucoma. This article describes the methodology adopted in LVPEI-GLEAMS. Methods: A sample of 3833 participants aged 40 years and older has been estimated to be enrolled using a compact segment sampling method with probability proportionate to size. Each participant will undergo a complete medical history and comprehensive eye examination including slit lamp photography, imaging of anterior and posterior segment, frequency doubling technology and standard automated perimetry. Additionally, glycosylated hemoglobin will be measured and a genetic profile based on candidate gene analysis will be undertaken. Clinical, biochemical and genetic data will be stored in a computerized database and analyzed. The novelty of this study lies in the fact that it is conducted at a vision center (primary eye care center serving a population of 50,000) by a vision technician (high school educated rural youth trained in basic ophthalmic techniques for a year). Conclusion: Information from the diagnostic techniques of the study will be used to develop effective community-level screening strategies, and insights from risk factors associated with glaucoma will help develop appropriate detection and management strategies.

25g Pars Plana Vitrectomy And Irido-zonulo-hyaloido-vitrectomy In The Management Of Malignant Glaucoma In Phakic Eyes Following Trabeculectomy.

Purpose: To describe a new surgical technique in the management of malignant glaucoma in phakic eyes. Methods: We performed 25-gauge pars plana vitrectomy with anterior irido-zonulo-hyaloido-vitrectomy in 2 young phakic patients with malignant glaucoma after trabeculectomy. This technique allowed posteroanterior aqueous communication, relieved aqueous misdirection, helped restoring anterior chamber depth, normalized the intraocular pressure and most importantly helped to preserve the crystalline lens. Results: At 8 months follow-up, both patients have stable visual acuity, normal intraocular pressure, well-functioning blebs, and clear crystalline lens. Conclusion: One can consider 25-gauge pars plana vitrectomy with anterior irido-zonulo-hyaloido-vitrectomy as a safe and effective treatment option for the management of malignant glaucoma in phakic eyes.

Comparison of Cataract Surgery Alone Versus Cataract Surgery Combined With Trabeculectomy in the Management of Phacomorphic Glaucoma.

Purpose:To compare the outcomes of cataract surgery alone versus combined cataract surgery with trabeculectomy in eyes with phacomorphic glaucoma. Materials and Methods:In a retrospective comparative case series, 126 eyes of phacomorphic glaucoma presenting within 4 weeks of onset between 1993 and 2012, with at least 6 months of postoperative follow-up were included. Group 1 included 63 eyes with cataract surgery only and group 2 included 63 eyes with combined cataract surgery and trabeculectomy. Primary outcome measure was intraocular pressure (IOP) ⩽21 mm Hg (without antiglaucoma medication) 6 months after surgery. Results:The median (interquartile range) preoperative IOP in group 1 was 36 mm Hg (30 to 50 mm Hg) and group 2 was 40 mm Hg (32 to 48 mm Hg) (P=0.34). The median duration of phacomorphic attack was 7 days (3 to 12 d) in group 1 and 7 days (3 to 15 d) in group 2 (P=0.39). The median duration of postoperative follow-up was 23 months in group 1 and 30 months in group 2 (P=0.89). Six months after surgery, 97% of the eyes in group 1 and 100% in group 2 achieved IOP⩽21 mm Hg without antiglaucoma medications with a median postoperative IOP of 12 mm Hg in both the groups (P=0.09). The median Log MAR visual acuity was significantly better in group 1 compared with group 2 (0.2 vs. 0.3, P<0.001). The percentage of eyes that achieved visual acuity better than 20/40 at 3 months was 62% in group 1 versus 19% in group 2 and at 6 months it was 75% in group 1 versus 38% in group 2 (P<0.001). Conclusions:In our cohort of phacomorphic glaucoma presenting within 4 weeks of onset, cataract surgery and combined surgery resulted in similar IOP control at 6 months. However, cataract surgery alone resulted in better and faster visual recovery.