Scanning laser polarimetry in glaucoma.

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White‑on‑white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

Novel occurrence of Axenfeld: Rieger syndrome in a patient with blepharophimosis ptosis epicanthus inversus syndrome.

is a complex eyelid malformation characterized by the classical tetrad of blepharophimosis, telecanthus, ptosis, and epicanthus inversus. It has been reported to be associated with other ocular anomalies such as euryblepharon, strabismus, nystagmus, amblyopia, microphthalmos, lacrimal drainage apparatus abnormality, extra ocular muscle abnormalities, microcornea, trabecular dysgenesis, optic nerve hypoplasias, and colobomas of the optic disk. We describe a case of BPES with Axenfeld–Rieger syndrome, a neurocristopathy characterized by maldevelopment of the anterior segment with predisposition to development of glaucoma. Interestingly, both syndromes are caused by mutations in the same class of genes, namely the winged‑helix/ forked transcription factors (FOX) involved in a variety of developmental processes.

Test retest variability of TonoPen AVIA.

The study was conducted to evaluate the intra-session repeatability of Tonopen AVIA (TPA). 180 eyes of 180 patients (50 eyes with glaucoma, 130 eyes of controls) were recruited for this observational study. The mean age of patients enrolled in the study was 43.9 ± 16.7 yrs (84 males, 96 females). Mean IOP recorded with Tonopen AVIA was 19.5 ± 9.5 mmHg, 19.4 ± 9.6 mmHg and 19.3 ± 9.2 mmHg, respectively in the first, second and third instances (P = 0.656). The intraclass correlation coefficient (ICC) ranged from 0.996 (95% CI: 0.956 - 0.998) for glaucoma subjects to 0.958 (95% CI: 0.934 - 0.975) for controls. The coefficient of variation in the study population ranged from 3.47% (glaucoma patients) to 8.10% (healthy controls), being 6.07% overall. The coefficient of repeatability varied between 2.96 (glaucoma patients), 3.35 (healthy controls) to 3.24 (overall). Thus, the Tonopen Avia shows good intrasessional repeatability of IOP in both glaucomatous patients and healthy subjects.

Anatomical and functional graft survival, 10 years after epikeratoplasty in keratoconus.

Purpose: To report outcomes of epikeratoplasty in keratoconus (KC), utilizing manually-prepared plano donor lenticules in terms of flattening of the cone, reduction in astigmatism and improvement in the visual acuity. Materials and Methods: Patients with KC, having visual acuity <20/200, astigmatism >12 diopters (D) but without corneal opacity underwent epikeratoplasty, using manually prepared plano donor lenticules from fresh or M.K preserved corneas, between 1990 - 2000 and followed for 10 years, were included in this report. Visual acuity slit-lamp-biomicroscopy, keratometry, and refraction were performed at 8 weeks, 12 weeks, and 6 months for all 59 patients. The same were carried out at 1 year, 5 years, and 10 years depending upon the availability of the patient for that period. Results: Of the 59 patients, only 26 were available for follow-up after 10 years. At 3 months, 1 year and 5 years, best corrected visual acuity of (BCVA) ≥20/60 were achieved in 84.7%, 84.4% and 80.3% of eyes, respectively. BCVA was 73% at 10-year follow- up, which was due to the presence of posterior subcapsular cataract (PSC). The average keratometric astigmatism and average flattening in diopters stabilized at the end of 3 months, which remained constant at 1, 5, and 10-year follow-up. The average diopter of myopia was stabilized by 1 year, which was almost same at 10 year. Graft was clear in all but 1 eye at 10 year follow-up. Conclusion: Epikeratoplasty is a useful technique for keratoconic eyes without apical scarring who fail or unable to use contact lenses.

Ocular Chlamydia trachomatis infections in patients attending a tertiary eye care hospital in north India A twelve year study.

Background & objectives: Ocular infection with Chlamydia trachomatis is a major public health problem in densely populated countries like India. The true prevalence of such infections is uncertain due to insufficient data available from India. The aim of this study was to do a retrospective analysis of C. trachomatis eye infections in patients attending the outpatient department of Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, over a period of 12 years. Methods: From 1997 to 2008, the Chlamydia laboratory received conjunctival swabs from 1281 consecutive patients for C. trachomatis detection after thorough clinical examination. Specimens were subjected to direct fluorescent antigen detection assay using monoclonal antibody based commercial kit to detect the presence of C. trachomatis antigen. Results: Antigen positivity varied between 22-28 per cent. Children below 11 yr and people above the age of 60 yr showed comparatively higher antigen positivity (25.7 and 27.8%, respectively). As compared to males significantly (P<0.05) higher number of females in the age group of 31-60 yr were positive for C. trachomatis antigen. Patients with the clinical diagnosis of follicular/allergic conjunctivitis and trachoma showed higher rate of antigen positivity. Interpretation & conclusions: Northern India having dry and arid climatic conditions in most parts of the year was considered in the past as one of the trachoma hyper-endemic foci. The study indicated that laboratory proven C. trachomatis eye infection still persisted in this part of the country throughout the study period of 12 years.

Prevalence of plateau iris configuration in primary angle closure glaucoma using ultrasound biomicroscopy in the Indian population.

Purpose: To report the prevalence of plateau iris in patients with primary angle closure glaucoma (PACG), in North India. Materials and Methods: The patients with PACG, attending the glaucoma services at a tertiary care center in North India were included in the study. All patients had undergone Nd-YAG laser peripheral iridotomy at least four weeks prior to inclusion in the study. Four weeks prior to inclusion in the study, none of the patients had used pilocarpine. Ultrasound Biomicroscopy (UBM) images were qualitatively evaluated and plateau iris configuration was defined in an eye if the following criteria were fulfilled in two or more quadrants: anteriorly directed ciliary process supporting the peripheral iris, steep rise of iris root from its point of insertion followed by a downward angulation from the corneoscleral wall, absent ciliary sulcus, and iridotrabecular contact in the same quadrant. Results: One hundred and one eyes were included in the study. There were 63 (62.4%) females and 38 (37.6%) males. The mean age of the patients was 57.8 ± 9.5 years (range: 42 to 78 years). The mean axial length in the study population was 22.2 ± 1.1 mm. The mean spherical equivalent refraction was 0.06 ± 1.12 D. The mean intraocular pressure was 18.5 ± 4.7 mmHg (range: 12 – 24 mmHg). Twenty-nine (28.7%) subjects were diagnosed with plateau iris on the basis of above-defined criteria. Of the 29 eyes, 18 (62.1%) subjects had plateau iris in two quadrants, nine (31.03%) in three quadrants, and two (6.8%) had this configuration in all the four quadrants. Conclusions: Approximately 30% of the eyes with PACG had plateau iris on UBM. Plateau iris was very often the cause for residual angle closure following laser peripheral iridotomy in Indian eyes with PACG.

Can we overcome the challenges of sutures in lamellar keratoplasty.

Lamellar keratoplasty (LK) is a technique which can be followed for both tectonic and optical purposes. We describe a technique of sutureless anterior LK by fixing the donor lenticule to the recipient bed using fibrin glue. LK was performed in an eye with corneal opacity using the manual dissection method. The donor lenticule was cut with a microkeratome after fixing the corneoscleral rim in an artificial anterior chamber. The size of the donor lenticule was 8.5 mm and fixed to the recipient bed with fibrin glue. The surgical time was reduced significantly with this technique. There was an uneventful postoperative period during the follow-up of 12 months. Best corrected visual acuity improved from hand movement to 20/60. Thus, the use of fibrin glue for fixing the anterior lamellar lenticule is a viable option for both optical and anatomical purposes.

Ahmed glaucoma valve in post-penetrating-keratoplasty glaucoma: A critically evaluated prospective clinical study.

Aim: The aim was to evaluate the outcome of Ahmed glaucoma valve (AGV) in post-penetrating-keratoplasty glaucoma (PKPG). Materials and Methods: In this prospective study, 20 eyes of 20 adult patients with post-PKPG with intraocular pressure (IOP) >21 mmHg, on two or more antiglaucoma medications, underwent AG (model FP7) implantation and were followed up for a minimum of 6 months. Absolute success was defined as 5 <IOP <21 mmHg and qualified success as 5 <IOP <21 mmHg with medications or minor procedures. Results: The mean IOP decreased from 42.95 ± 10.24 to 17.69 ± 3.64 mmHg (P <0.001) and the use of medications dropped from 2.92 to 0.39 (P <0.001) after AGV implantation. The absolute success was achieved in 11 eyes and qualified success in 9. There was no significant change in best corrected visual acuity, graft clarity, or graft thickness. Six device-related complications occurred after AGV implantations which were successfully managed with medical or minor surgical therapy. Conclusions: Postkeratoplasty refractory glaucoma managed by AGV implantation revealed a satisfactory outcome up to 6 months of follow-up.

Comparison of the diagnostic ability of Moorfield’s regression analysis and glaucoma probability score using Heidelberg retinal tomograph III in eyes with primary open angle glaucoma.

Purpose: To compare the diagnostic performance of the Heidelberg retinal tomograph (HRT) glaucoma probability score (GPS) with that of Moorfield’s regression analysis (MRA). Materials and Methods: The study included 50 eyes of normal subjects and 50 eyes of subjects with early-to-moderate primary open angle glaucoma. Images were obtained by using HRT version 3.0. Results: The agreement coefficient (weighted k) for the overall MRA and GPS classification was 0.216 (95% CI: 0.119 – 0.315). The sensitivity and specificity were evaluated using the most specific (borderline results included as test negatives) and least specific criteria (borderline results included as test positives). The MRA sensitivity and specificity were 30.61 and 98% (most specific) and 57.14 and 98% (least specific). The GPS sensitivity and specificity were 81.63 and 73.47% (most specific) and 95.92 and 34.69% (least specific). The MRA gave a higher positive likelihood ratio (28.57 vs. 3.08) and the GPS gave a higher negative likelihood ratio (0.25 vs. 0.44).The sensitivity increased with increasing disc size for both MRA and GPS. Conclusions: There was a poor agreement between the overall MRA and GPS classifications. GPS tended to have higher sensitivities, lower specificities, and lower likelihood ratios than the MRA. The disc size should be taken into consideration when interpreting the results of HRT, as both the GPS and MRA showed decreased sensitivity for smaller discs and the GPS showed decreased specificity for larger discs.

Pars plana Ahmed glaucoma valve implantation with triamcinolone-assisted vitrectomy in refractory glaucomas.

Glaucoma drainage devices are an option in refractory glaucomas for control of intraocular pressure (IOP). We evaluated the outcome of pars plana Ahmed glaucoma valve along with triamcinolone-assisted vitrectomy in 11 eyes with uncontrolled IOP on maximum tolerable antiglaucoma therapy. The mean preoperative IOP of 33.64 ± 5.99 (range 26 to 44 mmHg) decreased to 17.09 ± 2.26 (range 14 to 20 mmHg) and 17.45 ± 1.81mm of Hg (range 14 to 24 mmHg) at 6 and 12 months following surgery. The mean number of antiglaucoma medications decreased from 3.27 ± 0.05 to 0.64 ± 0.67 and 0.55 ± 0.6 at 6 and 12 months following surgery.

Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC).

Purpose: To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India. Materials and Methods: Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI). Results: The mean age of subjects was 57.6 ± 11.7 years (18 males, 14 females). Mean TSNIT average thickness (μm) pre- and post-cataract surgery was 49.2 ± 14.1 and 56.5 ± 7.6 (P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 ± 15.3 and 21.6 ± 11.8 (P = 0.001). Conclusions: Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient.

Fibrin glue in ophthalmology.

Suturing is a time consuming task in ophthalmology and suture induced irritation and redness are frequent problems. Postoperative wound infection and corneal graft rejection are examples of possible suture related complications. To prevent these complications, ophthalmic surgeons are switching to sutureless surgery. A number of recent developments have established tissue adhesives like cyanoacrylate glue and fibrin glue as attractive alternatives to sutures. A possible and promising new application for tissue adhesives is to provide a platform for tissue engineering. Currently, tissue glue is being used for conjunctival closure following pterygium and strabismus surgery, forniceal reconstruction surgery, amniotic membrane transplantation, lamellar corneal grafting, closure of corneal perforations and descematoceles, management of conjunctival wound leaks after trabeculectomy, lid surgery, adnexal surgery and as a hemostat to minimise bleeding. The purpose of this review is to discuss the currently available information on fibrin glue.

Post-penetrating keratoplasty glaucoma.

Post-penetrating keratoplasty (post-PK) glaucoma is an important cause of irreversible visual loss and graft failure. The etiology for this disorder is multifactorial, and with the use of new diagnostic equipment, it is now possible to elucidate the exact pathophysiology of this condition. A clear understanding of the various mechanisms that operate during different time frames following PK is essential to chalk out the appropriate management algorithms. The various issues with regard to its management, including the putative risk factors, intraocular pressure (IOP) assessment post-PK, difficulties in monitoring with regard to the visual fields and optic nerve evaluation, are discussed. A step-wise approach to management starting from the medical management to surgery with and without metabolites and the various cycloablative procedures in cases of failed filtering procedures and excessive perilimbal scarring is presented. Finally, the important issue of minimizing the incidence of glaucoma following PK, especially through the use of oversized grafts and iris tightening procedures in the form of concomitant iridoplasty are emphasized. It is important to weigh the risk-benefit ratio of any modality used in the treatment of this condition as procedures aimed at IOP reduction, namely trabeculectomy with antimetabolites, and glaucoma drainage devices can trigger graft rejection, whereas cyclodestructive procedures can not only cause graft failure but also precipitate phthisis bulbi. Watchful expectancy and optimal time of intervention can salvage both graft and vision in this challenging condition.

Immunohistochemical localization of human papilloma virus in conjunctival neoplasias: a retrospective study.

BACKGROUND: The extent of association of human papilloma virus (HPV) in human conjunctival neoplasias has been debated in studies originating from different parts of the world, but no substantial evidence has been generated on Indian subjects. This prompted us to carry out a retrospective study on conjunctival neoplasias diagnosed over the past 12 years. MATERIALS AND METHODS: Histopathological and immunohistochemical analysis of 65 specimens of ocular neoplasias and 30 normal controls diagnosed between 1991 and 2002 at a tertiary eye care hospital, was undertaken. Formalin-fixed, paraffin-embedded tissues were reviewed for confirming histopathological diagnosis, presence of koilocytosis and changes related to actinic keratosis. Immunohistochemical analysis was done using HPV-specific monoclonal antibodies. Clinicopathological correlation and the association of HPV antigen with the histopathological features were performed. RESULTS: Out of the 65 cases analyzed, 35 were papillomas and 30 were ocular surface squamous neoplasias (OSSN). The mean age was 48 years with a male preponderance. Histologically, koilocytosis was observed in 17.1% of papillomas and 36.6% of OSSN. Actinic keratosis was present in 33% of OSSN. Immunohistochemically 17.1% conjunctival papillomas stained positive for HPV antigen, all cases of OSSN were negative for HPV. There was no correlation between koilocytosis or actinic keratosis and the detection of HPV antigen. CONCLUSIONS: The association between HPV and conjunctival neoplasias is variable in different geographical areas and also depends on the methods of detection used. This study warrants the need for applying more advanced techniques at a molecular level to determine the possible etiology of HPV in conjunctival neoplasias among Asian-Indians.

Bilateral dissociated vertical deviation in a case of congenital hereditary endothelial dystrophy.

Dissociated vertical deviation (DVD) is an intermittent anomaly of the non-fixing eye. Although association of DVD with sensory visual deprivation owing to congenital or acquired opacities of the ocular media has been reported, its association with congenital hereditary endothelial dystrophy (CHED) has not been reported hitherto. We report a case having a bilateral asymmetric DVD, in a know case of bilateral CHED.