Applicability of the ISNT and IST rules on retinal nerve fiber layer measurement on spectral-domain optical coherence tomography in normal Indian children.

BACKGROUND: To determine the applicability of the ISNT (inferior>superior>nasal>temporal) and IST (inferior>superior>temporal) rules on retinal nerve fiber layer (RNFL) measurement on spectral-domain optical coherence tomography (SD-OCT) in normal children. METHODS: A prospective, cross-sectional study including consecutive subjects between the ages of 5-18 years who were born at term (≥37 weeks gestational age) and with a normal birth weight (≥2500 g) presenting to the out-patient department for refractive error examination. RNFL measurement was done on Spectralis SD-OCT. Exclusion criteria were best-corrected visual acuity less than 20/20, spherical equivalent (SE) > ± 5 diopter (D), applanation IOP >21 mmHg, cup-to-disc (C/D) ratio of >0.5, C/D ratio asymmetry of >0.2 between eyes and any retinal or optic disc anomaly as determined by mydriatic fundus examination. Subjects with amblyopia, strabismus, or family history of optic nerve or retinal disease were excluded. Poor cooperation for SDOCT imaging and lack of consent were other exclusion criteria. RESULTS: The ISNT rule on the RNFL was followed only by 30 eyes (23.8 %), while the IST rule was followed by 66 eyes (52.4 %) (p < 0.001). The superior RNFL was thicker than the inferior in 57 eyes (45.2 %) while the temporal RNFL was thicker than the nasal in 63 eyes (50 %). The age, gender, spherical equivalent, and disc size did not predict the followability of the ISNT and IST rules (p > 0.05). CONCLUSIONS: The ISNT and the IST rules for RNFL are not universally followed by all normal eyes in children. All deviations should therefore not be considered pathological.

Treatment outcomes in malignant glaucoma.

PURPOSE: To report treatment outcomes in malignant glaucoma. DESIGN: Retrospective case series. PARTICIPANTS: Twenty-eight eyes of 26 patients who were treated for malignant glaucoma between 1991 and 2009. METHODS: Malignant glaucoma was diagnosed based on the presence of a shallow or flat central and peripheral anterior chamber in the presence of patent iridotomy, with intraocular pressure (IOP) of 22 mmHg or more after any intraocular surgery. The treatment algorithm included antiglaucoma medications and cycloplegics as first-line methods; the second-line therapy in pseudophakic eyes was laser hyaloidotomy, followed by vitrectomy-hyaloidotomy-iridectomy (VHI) or transscleral cyclophotocoagulation (TSCPC). MAIN OUTCOME MEASURES: Resolution was defined as deepening of the central anterior chamber and IOP of 21 mmHg or less (on 2 successive follow-ups at least 1 week apart) with or without topical antiglaucoma medications in the absence of systemic antiglaucoma medications. RESULTS: At the diagnosis of malignant glaucoma, 5 eyes were phakic and 23 were pseudophakic. The preceding surgeries were trabeculectomy (11 eyes), cataract surgery (10 eyes), and combined cataract and glaucoma surgery (7 eyes). Mean IOP decreased from 34 ± 8.3 mmHg at presentation to 14.3 ± 5.2 mmHg at the last visit (P<0.001). Resolution of malignant glaucoma was seen in 27 eyes (27/28; 96%), 17 eyes resolved with 1 intervention, and 10 eyes required repeat procedures. Of the 27 eyes whose disease resolved, this result was achieved in 4 eyes with medical treatment, in 7 pseudophakic eyes with laser hyaloidotomy, in 4 eyes with VHI, and in 12 eyes with TSCPC. The median duration of follow-up was 192 days (interquartile range, 35-425 days). There was no difference in the visual acuity at presentation and at the final visit in 14 eyes. Eight eyes gained 2 lines or more and 6 eyes lost 2 lines or more of visual acuity. CONCLUSIONS: Malignant glaucoma can be managed successfully by appropriate and timely interventions. Medical treatment was beneficial in phakic eyes, laser hyaloidotomy was beneficial in pseudophakic eyes, and vitrectomy and TSCPC were beneficial in refractory cases. A stepladder approach to treatment was successful (96%) in this series. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Comparing keratometry readings with manual separation of lids and wire speculum in children under general anesthesia.

Purpose: Keratometry (K) readings are crucial for intraocular lens power calculation in cataract surgery. In children who do not cooperate, the keratometry is done under general anesthesia with a handheld autokeratometer. However, there is little consensus regarding the method for the measurement of K readings. The lids can be separated either by fingers or a wire speculum may be placed to separate the lids for measurement. Methods: The children selected for the study were patients cooperative for keratometry reading. Nidek KM-500 handheld keratometer was used first in the awake period. Then under general anesthesia, readings were taken first by separating the lids manually with fingers and then after putting a wire speculum in both the eyes. Results: The average keratometry reading for participants in the OPD, anesthetized with lids manually opened and with lids separated with speculum was 44.7 ± 1.7 D, 44.4 ± 1.9 D, and 44.7 ± 1.7 D, respectively. Conclusion: No significant change was observed in keratometry values in children with manual separation of eyelids or with wire speculum.

A novel simplified method for managing inadvertent tube cut during aurolab aqueous drainage implant surgery for refractory glaucoma.

We report a novel simplified method for managing inadvertent tube cut in a patient undergoing the Aurolab aqueous drainage implant (AADI) surgery for refractory neovascular glaucoma. Tube cut occurred while applying the polyglactin ligature suture used to avoid early postoperative hypotony. The short end of the cut tube was removed and the long end reinserted into the base plate of AADI. The surgery was then completed as usual. Following the surgery, the intraocular pressure reduced to 20 mmHg which stabilized and was maintained at 10 mmHg till the last follow-up at 12 months without any glaucoma medication.

The subjectivity of objective evaluation of torsion on fundus photographs by practicing strabismologists.

Purpose: To assess the variability of assessing the ocular torsion on fundus photographs among strabismus surgeons. Methods: This was a prospective, noninterventional, clinical trial involving 16 trained and experienced squint surgeons participated in the study. Two videos were prepared of a total of 10 fundus pictures with or without lines for disc foveal angle. The first video had a 4 s viewing time for each fundus image. The second video had the disc foveal lines drawn and a similar 4 s viewing time for each image. The participants were asked to grade the torsion. The primary outcome measure was to assess the agreement between the raters for ocular torsion measurement. Difference in the response of observers from the standard response was the secondary outcome measure. Results: A 4 s viewing time was given to mimic the exposure time in the clinic while assessing torsion in a patient. Large variability was found among the responses. The kappa test was done for comparing the agreement between various observers which ranged from slight to fair (<0.40). There was no difference in torsion grading in 30.6% and 26.3% responses in the first and second video from the standard response, respectively. When a limit of ±1 grade was taken as acceptable for the responses, 66.2% for the first and 68.7% for the second video respectively were similar to standard response. Conclusion: There is wide variability in assessing ocular torsion by fundus photography. The level of accuracy does increase with marking the line on photographs but still remains unreliable.

Spectacle prescription in children: Understanding practical approach of Indian ophthalmologists.

Purpose: The aim of this study is to survey the management approach, regarding spectacle prescription in children, among Indian ophthalmologists. Methods: A web-based, anonymous questionnaire (multiple choice questions dealing with practical aspects of pediatric refraction), was sent to available database of Indian ophthalmologists. The survey responses (depicted in %) were compared using the amount of pediatric clientele in one's practice (Group A: <25%, Group B: 25% or more). The responses were also analyzed in relation to the published concepts from literature. Results: Two hundred and ten ophthalmologists (2.74% response rate; 48% in Group A), from all over India, responded to the survey. There were wide discrepancies in the responses (both, in and among, Groups A and B; P > 0.05, Chi-square test), as to when and how much refractive error to prescribe in children, for a given situation. Conclusion: A wide gap exists between pediatric spectacle prescription patterns of Indian ophthalmologists, as compared to the recommended pediatric ophthalmology protocols. The management approach, for certain situations concerning the pediatric refraction, was better among those with higher pediatric clientele.

Asymmetry of Retinal Nerve Fiber Layer and Posterior Pole Asymmetry Analysis Parameters of Spectral Domain Optical Coherence Tomography in Children.

PURPOSE: To determine inter- and intraocular differences in the retinal nerve fiber (RNFL) and posterior pole asymmetry analysis (PPAA) macular thickness parameters in children using spectral domain optical coherence tomography. METHOD: A prospective, cross-sectional study involving 126 subjects between the age group of 5-15 years received a standardized eye examination including spectral domain optical coherence tomography for retinal nerve fiber layer and macular thickness measurements. Asymmetry was calculated as the difference between the right and left eyes as well as the superior and inferior area of one randomly selected eye for each subject. Normal ranges were established as the 2.5 and the 97.5 percentiles. Correlation between the right and left eyes were assessed by intraclass correlation coefficients. RESULTS: The difference in the average and superior RNFL between the right and the left eye was not statistically significant. The interocular 2.5 and 97.5 percentile limits for RNFL thickness and total PPAA macular thickness were -7.75 to 12.5 microns and -9 to 21 microns, respectively. The 2.5 and 97.5 percentile limits of the intraocular superior-inferior area difference for the RNFL thickness and PPAA macular thickness were -40 to 37 microns and -32 to 38 microns, respectively. A strong correlation for all parameters between the right and the left eye was seen. CONCLUSION: The normal interocular RNFL and PPAA macular thickness asymmetry should not exceed 12.5 microns and 21 microns, respectively. Similar intraocular limits for superior-inferior asymmetry should not exceed 40 and 38 microns, respectively.

The applicability of correction factor for corneal thickness on non-contact tonometer measured intraocular pressure in LASIK treated eyes.

PURPOSE: To determine the applicability of central corneal thickness (CCT) based correction factor for non-contact tonometer (NCT) measured intraocular pressure (IOP) readings. METHOD: A prospective, non-randomized study involved 346 eyes of 173 consecutive patients with age ⩾21 years undergoing laser-assisted in situ keratomileusis (LASIK) for myopia and/or myopic astigmatism. The CCT and IOP were measured before and after the LASIK procedure. The IOP pre and post-LASIK was compared after applying the correction factor for CCT. Patients not completing the 3 month postoperative follow-up were excluded. RESULTS: The median spherical equivalent before undergoing LASIK was -4.25D (inter-quartile range, -3.25D). The mean preoperative CCT was 536.82 ± 33.71 µm which reduced to 477.55 ± 39.3 µm (p < 0.01) post-LASIK. The mean IOP reduced from a preoperative value of 14.6 ± 2.32 mmHg to 10.64 ± 2.45 mmHg postoperatively (p < 0.01). On applying correction for the corneal thickness, the pre and postoperative IOP was 15.14 ± 2.8 mmHg and 15.37 ± 2.65 mmHg (p = 0.06) respectively with a strong positive correlation (r = 0.7, p < 0.01). Three hundred eyes (86.7%) had an absolute difference in IOP of less than 3.0 mmHg post-CCT correction which is within the retest variability of NCT. Only 46 eyes (13.3%) had an absolute difference of more than 3.0 mmHg. CONCLUSION: The modified Ehler's correction algorithm used in this study can be effectively applied in the normal IOP range in a majority of patients.

Diagnostic accuracy of posterior pole asymmetry analysis parameters of spectralis optical coherence tomography in detecting early unilateral glaucoma.

PURPOSE: To report the diagnostic ability of posterior pole asymmetry analysis (PPAA) parameters of spectralis optical coherence tomography (OCT) in detecting early unilateral glaucoma. METHODS: A prospective, cross-sectional study which included 80 eyes of 80 normal subjects and 76 eyes of 76 patients with unilateral early primary open-angle glaucoma by Hodapp-Anderson-Parrish classification. All subjects were of age more than 18 years, best-corrected visual acuity 20/40 or better, and a refractive error within ± 5 diopter (D) sphere and ± 3 D cylinder. Control subjects had a normal ocular examination, intraocular pressure (IOP) <22 mmHg, no past history of high IOP, no family history of glaucoma, normal optic disc morphology, and visual field in both eyes. One eye of the control subject was randomly included. All eyes underwent OCT for retinal nerve fiber layer (RNFL) analysis and PPAA. The number of continuous black squares was noted in the asymmetry analysis (right-left + hemisphere asymmetry). The area under curve (AUC) was calculated for all OCT parameters. RESULTS: The best value for AUC for RNFL analysis was 0.858 for the inferotemporal quadrant thickness. This was similar to the best value for AUC for PPAA which was 0.833 for the inferior macular thickness parameter (P = 0.5). The AUC for the right-left and the hemisphere asymmetry part of PPAA was 0.427 and 0.499, respectively. CONCLUSION: The macular thickness PPAA parameters were equally good as the RNFL parameters. However, the asymmetry analysis parameters performed poorly and need further refinement before its use in early unilateral glaucoma diagnosis.

Applicability of ISNT and IST rules to the retinal nerve fibre layer using spectral domain optical coherence tomography in early glaucoma.

BACKGROUND: To report the applicability of ISNT (inferior>superior>nasal>temporal) and IST (inferior>superior>temporal) rules on the retinal nerve fibre layer (RNFL) using spectral domain optical coherence tomography (SD-OCT) for detecting early glaucoma. METHODS: A prospective, cross-sectional study which included 80 eyes of 80 normal subjects and 76 eyes of 76 patients with early glaucoma by Hodapp-Anderson-Parrish classification. All subjects were of age more than 18 years, best corrected visual acuity 20/40 or better and a refractive error within ±5 dioptres (D) sphere and ±3 D cylinder. Control subjects had a normal ocular examination, intraocular pressure <22 mm Hg, no past history of high intraocular pressure, no family history of glaucoma, normal optic disc morphology and visual field. All eyes underwent SD-OCT examination for RNFL analysis. The sensitivity, specificity and likelihood ratio for violation of ISNT and IST rules was calculated for early glaucoma diagnosis. RESULTS: The ISNT rule was followed by 44 (55%) normal and 28 (36.84%) early glaucoma eyes. The IST rule was followed by 48 (60%) normal and 40 (52.63%) early glaucoma eyes. The sensitivity/specificity for violation of ISNT and IST rules for early glaucoma diagnosis was 63.2%/55% and 47.4%/60% respectively. The positive/negative likelihood ratio for ISNT and IST rules was 1.4/0.67 and 1.2/0.88, respectively, for diagnosing early glaucoma. CONCLUSIONS: Even though useful during ophthalmoscopy, ISNT and IST rules by themselves don't clearly distinguish normal eyes from those with glaucoma when applied to the quadrant values on RNFL on SD-OCT examination.

A technique for standardizing disk foveal angle measurement.

Ocular torsion can been measured by perimetry, double Maddox rod, Bagolini glasses, indirect ophthalmoscopy lens, slit-lamp biomicroscopy, synoptophore, and fundus photography. Wide variations have been reported in the measurement of the disk foveal angle (DFA) using fundus photography. We describe a technique for measuring the DFA, formed by a horizontal line extending from the center of the optic disk and a line from the center of disk to the fovea, using Microsoft PowerPoint and ImageJ software.

Recurrence of aqueous misdirection following pars plana vitrectomy in pseudophakic eyes.

We present a retrospective interventional case series of four patients with pseudophakic eye who developed recurrent aqueous misdirection following pars plana vitrectomy (PPV) for malignant glaucoma (MG). The patients were treated with neodymium: YAG (Yttrium Aluminum Garnet) laser hyaloidotomy/membranotomy through the patent peripheral iridectomy. The main outcome measure was resolution of MG. The intervention resulted in resolution of MG in all four cases. The cause for recurrence was an inflammatory membrane covering the hyaloidotomy opening in three eyes and the haptic of intraocular lens blocking the hyaloidotomy opening in one eye. Recurrence of aqueous misdirection even after vitrectomy may be related to obstruction of aqueous flow through the communication created, either by intraocular lens or fibrin. Treatment of this condition involves restoring aqueous flow to the anterior chamber from the anterior vitreous by treating the cause, and most often the YAG laser hyaloidotomy/membranotomy is successful in relieving the condition.

Outcomes of Ahmed valve implant following a failed initial trabeculotomy and trabeculectomy in refractory primary congenital glaucoma.

PURPOSE: The aim was to report the outcome of Ahmed glaucoma valve (AGV) (New World Medical, Inc., Rancho Cucamonga, CA, USA) implantation as a surgical intervention following an initial failed combined trabeculotomy + trabeculectomy (trab + trab) in refractory primary congenital glaucoma (RPCG). MATERIALS AND METHODS: Retrospective chart review of 11 eyes of 8 patients who underwent implantation of AGV (model FP8) for RPCG between 2009 and 2011. Prior trab + trab had failed in all the eyes. Success was defined as an intraocular pressure (IOP) >5 and ≤ 18 mmHg during examination under anesthesia with or without medications and without serious complications or additional glaucoma surgery. RESULTS: The mean age at AGV implantation was 15.4 ± 4.9 months. The mean preoperative IOP was 28 ± 5.7 mmHg which reduced to 13.6 ± 3.4 mmHg postoperatively at the last follow-up (P < 0.0001). The number of topical antiglaucoma medications reduced from a mean of 2.6 ± 0.5 to 1.6 ± 0.9 postoperatively (P = 0.009). The definition of qualified success was met in 10 (90%) eyes. One eye developed a shallow anterior chamber with choroidal detachment at 1-week, which resolved spontaneously with medications. None of the eyes developed a hypertensive phase. One eye had a long tube resulting in tube corneal touch that required trimming of the tube. One eye developed tube retraction, which was treated with a tube extender. The mean follow-up was 17.9 ± 9.3 (6.2-35.4) months. CONCLUSION: Managing RPCG remains a challenge. AGV implant was successful in a significant proportion of cases.

Effect of nepafenac eye drops on intraocular pressure: a randomized prospective study.

PURPOSE: To report the effect of nepafenac (0.1%) eye drops on intraocular pressure in eyes with cataract. DESIGN: Prospective randomized clinical trial. METHODS: Three hundred and twenty-seven patients with bilateral cataracts in an institutional setting were included. All patients had a baseline intraocular pressure (IOP) ≤ 21 mm Hg without a history of intraocular surgery in the past 3 months. One eye of each individual was randomized to the treatment group, with the other eye acting as a control. Nepafenac (0.1%) eye drops were instilled 3 times a day in the eye that received treatment. Intraocular pressure (IOP) with Goldmann applanation tonometer (GAT) was measured at baseline and at 4 and 8 weeks. Proportion of eyes with an IOP elevation of >4 mm Hg was the main outcome measure. RESULTS: The mean age of the participants was 45.7 ± 4.4 years. Participants included 192 female and 135 male patients. The mean IOP at baseline in the treated and control eyes was, respectively, 13.8 ± 2.5 mm Hg and 13.4 ± 3.0 mm Hg, which reduced to 12.0 ± 2.0 mm Hg and 12.1 ± 1.5 mm Hg, respectively, at the end of 8 weeks. This reduction in IOP in both groups was significant (P < .01). The difference between the IOP in the treated and control eyes at 8 weeks was not statistically significant (P = .34). One eye in the treated group and 2 eyes in the control group had an IOP elevation of >4 mm Hg. CONCLUSION: Nepafenac eye drops do not increase the IOP. They can possibly be used as an alternative to steroid medications where steroid responsiveness is a concern.