Amit Sobti

Application of anterior segment optical coherence tomography in glaucoma.

Optical coherence tomography (OCT) is a cross-sectional, three-dimensional, high-resolution imaging modality that uses low coherence interferometry to achieve axial resolution in the range of 3-20 μm. Two OCT platforms have been developed: time domain (TD-OCT) and spectral (or Fourier) domain (SD/FD-OCT). Visante anterior segment OCT (Carl Zeiss Meditec) is a TD-OCT widely used for anterior segment imaging. The SD-OCT systems with both posterior and anterior segment imaging capabilities include the RTVue, iVue (Optovue), the Cirrus (Carl Zeiss Meditec), and the Spectralis (Heidelberg Engineering, Inc.). Each of the SD-OCTs has a wavelength in the range of 820-879 nm. Anterior segment OCT is a non-contact method providing high resolution tomographic cross-sectional imaging of anterior segment structures. Anterior segment OCT provides qualitative and quantitative assessment of the anterior segment structures important to the pathogenesis and the anatomical variations of glaucoma, and the approach to and success of treatment. We summarize the clinical applications of anterior segment OCT in glaucoma.

Course and Outcome of Accidental Sodium Hydroxide Ocular Injury

PURPOSE To evaluate the course and outcome of patients with accidental ocular alkali burns. DESIGN Prospective, interventional case series. METHODS Study of a cohort of 16 patients (31 eyes) who sustained concomitant accidental sodium hydroxide ocular burns and received appropriate treatment at a tertiary care eye hospital in India. The patients were followed up for 1 year, and parameters including best-corrected visual acuity, epithelial defect area, conjunctival and limbal involvement, and injury-related complications were evaluated. RESULTS Severe sodium hydroxide exposure of a mean duration of 12 ± 2.5 minutes and delay in specialist eye care caused moderate to severe injury (grade II, 19% [n = 6]; grade III, 19% [n = 6]; grade IV, 10% [n = 3]; and grade VI, 52% [n = 16]). Median best-corrected visual acuity at presentation was 1.0 logarithm of the minimal angle of resolution (logMAR) units (range, 0.3 to 1.9 logMAR units), and at 1 year, it was 1.0 logMAR units (range, 0 to 1.9 logMAR units; P = .121). The median initial epithelial defect was 100 mm(2) (range, 18 to 121 mm(2)), which healed in all eyes by 3.5 months. Initial median limbal involvement was 12 clock hours (range, 3 to 12 clock hours), resulting in a residual limbal stem cell deficiency of 6 clock hours (range, 0 to 12 clock hours) at 1 year. Most common complications were glaucoma and cataract. Corneal ulcers developed in 2 eyes, and keratolimbal graft was performed in 1 patient. Grade VI injuries had significantly worse outcome than the lower-grade injuries. CONCLUSIONS The course and outcome of ocular alkali burns depends on effective first aid (including a thorough eyewash), age, initial grade of injury, response to treatment, prevention of secondary infection, and control of glaucoma. Despite appropriate treatment, these eyes responded poorly and carried a guarded visual prognosis.

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.

Ultrasound biomicroscopic assessment of angle parameters in patients with primary angle closure glaucoma undergoing phacoemulsification.

Purpose To evaluate the effect of phacoemulsification and foldable intraocular lens (IOL) implantation on biometric determinants of the anterior chamber angle in primary angle closure glaucoma (PACG) using ultrasound biomicroscopy (UBM). Methods Forty-six eyes of 46 patients with chronic PACG and cataract having a patent laser iridotomy were included in this prospective, interventional case series. Angle parameters were measured using UBM before surgery and 3 months after phacoemulsification with IOL implantation. Intraocular pressure (IOP) was measured by applanation tonometer and records of glaucoma medication administered were maintained. Main outcome measures were IOP, central anterior chamber depth (ACD), trabecular iris angle (TIA), and angle opening distance at 250 and 500 μm from scleral spur (AOD250 and AOD500). Results The mean age of study participants was 56.5±9.9 years (range 44–75). The preoperative mean IOP was 25.0±5.4 mmHg on maximum antiglaucoma medication, which was reduced to 15.8±3.8 mmHg (p=0.0001) at 3 months. Number of antiglaucoma medications also decreased from 2.4±1.1 to 0.4±1.1 (p=0.0001). There was a significant widening of the anterior chamber angle with the TIA increasing significantly after phacoemulsification (p<0.001) with an associated increase in AOD250, AOD500, and ACD (p<0.001). Conclusions Phacoemulsification in eyes with PACG results in significant widening of the anterior chamber angle. This results in better IOP control after surgery and decreases the need for glaucoma medications. These findings are of clinical significance in obviating the need for simultaneous filtering surgery in eyes with PACG undergoing phacoemulsification cataract surgery.

Comparative evaluation of Diaton and Goldmann applanation tonometers.

Aim: To evaluate the agreement between intra-ocular pressure (IOP) measurements with the Diaton and the Goldmann applanation tonometers (GAT). Methods: In this cross-sectional observational study, a total of 196 eyes of 196 participants (66 patients with glaucoma, 130 healthy subjects) were included. IOP measurements were obtained from all patients using the Diaton and GAT. Results: The average age of the patients enrolled in this study was 48.3 ± 14.6 years (range 18–79). The overall mean IOP measured by the Diaton was 17.2 ± 6.4 mm Hg, while that in glaucoma patients was 17.9 ± 6.2 mm Hg and in the control group 15.8 ± 4.9 mm Hg. Pearson’s correlation coefficient showed a moderate correlation in IOP measurements by the two instruments in healthy controls (r = 0.460, p < 0.01); however, the same correlation for the glaucomatous subjects was noted to be poor (r = 0.261, p = 0.57). The limits of agreement (95% confidence intervals) ranged from –9.9 to +11.2 and from –15.3 to +19.7 mm Hg in healthy controls and glaucoma patients, respectively. Conclusion: The Diaton measurements do not correlate well with those provided by applanation tonometry. The two tonometers show very wide limits of agreement so they may not be used interchangeably in clinical practice for the measurement of IOP.

Comparison of Tono-Pen AVIA intraocular pressure measurements performed at limbus with central corneal Tono-Pen AVIA intraocular pressure.

Purpose: To compare Tono-Pen AVIA (TPA) intraocular pressure (IOP) measurements performed at the limbus with central corneal Tono-Pen AVIA (TPA) intraocular pressure. Methods: Fifty-one patients attending our outpatient department with a best corrected visual acuity of ≥20/40, no corneal disease, and no astigmatism greater than 1.5 diopters underwent routine ophthalmological examination. Patients with ametropia greater than or equal to ±5 diopters, a history of recent contact lens wear, and central corneal thickness of <480 µm or >550 µm were excluded from the study. IOP was recorded first in the corneal center, followed by tonometry measurements obtained from the temporal, nasal, superior, and inferior limbus using TPA. IOP measurements were compared using the paired t test. Correlation was derived by Pearson correlation coefficient, and regression equations were derived. Results: The mean age of patients in our study was 43.86 ± 15.39 years. The mean TPA IOP from the central cornea was 16.59 ± 3.75 mm Hg. There was a statistically significant difference between Tono-Pen IOP from the central cornea and that recorded from all 4 limbal positions (P < 0.001). There was a positive correlation between the central and the limbal IOP obtained with Tono-Pen. Correlation was maximum for the temporal limbus. Conclusions: Limbal TPA IOP is significantly higher than central TPA IOP. There remains a good correlation between central and limbal IOP. This was found to be greatest for the temporal limbus.

Trypan blue staining of filtering bleb in eyes with operated trabeculectomy

OBJECTIVE To report the use of trypan blue staining of the filtering bleb to assess its functional status in eyes undergoing phacoemulsification after trabeculectomy. SUBJECTS AND METHODS This retrospective study was conducted at a tertiary eye care centre in North India and studied 33 eyes of 33 patients ( with previously operated trabeculectomy), who underwent phacoemulsification. Trypan blue dye (0.06%) was used to stain the anterior capsule. After completion of phacoemulsification, the staining of the trabeculectomy bleb was noted as diffuse, patchy, minimal or no staining. RESULTS Of the 33 eyes, 13 had diffuse staining (39.4%, mean IOP = 9.3 ± 2.2 mm Hg), 7 (21.2%, mean IOP= 15.5 ± 1.8 mm Hg) had patchy staining, 4 had minimal staining (12.1%, mean IOP= 17.5 ± 0.5mm Hg) and nine (27.3%, mean IOP= 19.3 ± 1.6 mm Hg) had no staining. These staining patterns were labeled as groups 1 - 4 respectively. Statistical analysis showed that the difference between the IOPs in Group 1 - 2 and between Group 2 - 3 was not significant statistically (p=0.682 and 0.665 respectively). However the differences between the IOPs between Groups 1 - 3, 1 - 4, 2 - 4, and 3 - 4 were found to be highly significant statistically (p less than 0.0005). CONCLUSIONS Trypan blue dye can be used to test the amount of sub conjunctival filtration in eyes undergoing phacoemulsification cataract surgery.

Evaluation of the effect of scleral buckling on the anterior chamber angle using ASOCT.

Purpose:To evaluate the change in anterior chamber angle parameters after scleral buckling surgery using anterior segment optical coherence tomography (ASOCT). Methods:Fifty-five phakic eyes of 55 subjects undergoing scleral buckling with the placement of an encircling band for primary rhegmatogenous retinal detachment were included in this study. Anterior chamber angle assessment was performed using ASOCT. The trabecular iris angle (TIA), the angle-opening distance, and the trabecular iris space area were the parameters obtained preoperatively and 48 hours, 1 week, and 1 month after the surgery using ASOCT. The intraocular pressure (IOP) was measured using Goldmann applanation tonometry. Results:The mean age of the patients was 43.2±11.3 years; there were 38 male and 17 female patients. There was a significant decrease in all the angle parameters (TIA, angle opening distance, and trabecular iris space area) at 48 hours, 1 week, and 1 month after surgery (P<0.0001). TIA 180 degree decreased from 41.93±14.27 degrees preoperatively to 31.09±10.52 degrees (P<0.0001) and TIA 0 degree from 42.7±14.04 degrees to 32.92±12.17 degrees (P<0.0001) at 48 hours postoperatively. The mean IOP at 48 hours (17.04±3.26 mm Hg) was significantly higher than the preoperative level (12.68±1.96 mm Hg; P<0.001). No significant difference was noted between the mean preoperative IOP and the IOP readings at 1 week (P=0.402) and 1 month (P=0.23) postoperatively. Conclusions:ASOCT imaging reveals that scleral buckling surgery for retinal detachment induces significant narrowing of the anterior chamber angle.

Gonioscopy : a text and atlas (with goniovideos)

Gonioscopy Text * Chapter 1: History * Chapter 2: Principle of Gonioscopy * Chapter 3: Indications of Gonioscopy * Chapter 4: Direct and Indirect Gonioscopy * Chapter 5: Slit Lamp Gonioscopy Techniques * Chapter 6: Special Gonioscopy Techniques * Chapter 7: Normal Gonioscopy Anatomy * Chapter 8: Gonioscopic Grading Systems * Chapter 9: Assessment of Angle Pathology - An Overview * Chapter 10: Primary Angle Closure Disease * Chapter 11: Primary Open Angle Glaucoma * Chapter 12: Congenital and Developmental Glaucoma * Chapter 13: Angle Pathologies * Chapter 14: Sterilization Techniques * Chapter 15: RetCam Gonioscopy Gonioscopy Atlas * Open Angle * Myopia * Angle Closure * Closed Angle Opening on Manipulation * Anterior Iris Insertion * Angle Recession * Aniridia * Anterior Chamber Intraocular Lens * Axenfeld-Rieger Syndrome * Blood in the Angle * Ciliary Body Melanoma * Corneal Wedge * Cotton Fibers in the Angle * Cyclodialysis * Express Implant * Fibrous Ingrowth * Foreign Body in the Angle * Goniosynechiae * Haptic of PC IOL in Angle through Iridectomy * Iridodialysis * Irido-fundal Coloboma * Iris Adherent to Cataract Surgical Wound * Iris Bombe * Iris PE Cyst Causing Segmental Angle Closure * Kayser-Fleischer Ring * Neovascularization of Angle * Ocular Ischemic Syndrome * Pigment Dispersion Syndrome * Plateau Iris Configuration with Double Hump Pattern * Post Cataract Surgery Gonioscopy * Post Surgical Angle Pigmentation * Post-traumatic Iridodialysis with Central PAS * Post-traumatic Angle Pigmentation * Prominent Iris Processes * Prominent Schwalbes line * Pseudophakia with Glaucoma * Pseudophakia with Glaucoma with AC IOL * Pseudotrabecular Meshwork in a Closed Angle * Sarcoidosis Nodules in the Angle * Secondary Angle Closure due to High Vaulted ICL * Sentinel Synechiae * Silicone Oil * Trabeculectomy Ostium * Uveitic Glaucoma * Vitreous Strands in the Angle * View of Ciliary Body and Peripheral Retina * Ahmed Glaucoma Valve DVD Contents * Angle Closure Glaucoma * Ahmed Glaucoma Valve * Angle Pigmentation in Pseudophakia * Angle Recession * Aniridia * Anterior Segment Dysgenesis * Axenfled-Rieger Syndrome * Anterior Chamber Iol Causing Angle Damage * Cyclodialysis * Broad Based Peripheral Anterior Synechiae * Foreign Body in Angle * Express Shunt * Fibrous Ingrowth in the Angle * Heavily Pigmented Trabecular Meshwork * Gonioscopy Techniques * High Myope with Wide Open Angle * Irido-Fundal Coloboma * Iridocorneal Endothelial Syndrome * Iridodialysis * Keratic Precipitates * Nodules in the Angle in Sarcoidosis Uveitis * Ocular Squamous Neoplasia Eroding the Angle * Ocular Ischemic Syndrome * Open Angle * Peripheral Retina in Aphakia * Pigment Epithelial Cyst Causing Segmental Angle Closure * Paracytic Cyst * PCIOL in Anterior Chamber Angle * Trabeculectomy Ostium Blockage * Pigment Clumps * Pigment Dispersion * Pigmentary Glaucoma * Tumor in the Angle * Prominent Iris Processes * Silicon Oil in the Angle * Trabeculectomy * Uveitis * Corneal Wedge * Koeppe Lens * Dynamic Gonioscopy

Repositioning of Ahmed glaucoma valve tube in the anterior chamber with prolene sutures to manage tube-endothelial touch.

BACKGROUND Corneal endothelial damage is a known complication of aqueous shunt surgery. OBJECTIVE To describe a new technique for repositioning the Ahmed glaucoma valve tube in a case of tube-endothelial touch. CASE A patient with advanced glaucoma, having undergone Ahmed glaucoma valve (AVG) implantation, developed localized corneal endothelial damage due to contact between the tube and superior corneal endothelium. Two 10-0 prolene anchor sutures were passed over the tube in the anterior chamber, repositioning it away from the endothelium, thus preventing further damage to the corneal endothelium. Resolution of corneal oedema was noted without affecting the tube drainage and intraocular pressure. CONCLUSION Intracameral repositioning of the shunt tube using prolene sutures is a useful technique for correcting the tube malposition.