Ramesh Kekunnaya

Cultivated Limbal Epithelial Transplantation in Children With Ocular Surface Burns

IMPORTANCE Although several reports are available on the use of conventional and cultured limbal epithelium using various substrates in the treatment of limbal stem cell deficiency (LSCD), the patient populations studied have been largely adults. Thus, to our knowledge, the outcomes of this procedure exclusively in a pediatric population have not been reported previously. OBJECTIVE To report the outcomes of autologous ex vivo cultivated limbal epithelial transplantation (CLET) in pediatric patients with LSCD after ocular burns. DESIGN AND SETTING A retrospective, interventional case series of patients treated at the L. V. Prasad Eye Institute, Hyderabad, India. PARTICIPANTS Children up to 15 years with LSCD secondary to chemical or thermal injury who underwent CLET from April 1, 2001, through June 31, 2010, with a follow-up of at least 1 year, were included in the study. INTERVENTION After a limbal biopsy specimen obtained from a healthy area of the limbus, the limbal epithelial cells were cultured on a denuded human amniotic membrane substrate using a xeno-free explant culture technique. A monolayer of cultivated epithelial cells along with the amniotic membrane was transplanted on the patients affected eye after pannus excision. In cases of failure, the same procedure was repeated. MAIN OUTCOMES AND MEASURES Ocular surface stability and visual improvement were the primary and secondary outcome measures, respectively. Success was defined as a stable corneal epithelium without conjunctivalization. Eyes with conjunctivalization and persistent epithelial defects were classified as failures. RESULTS Of the 107 eyes of 107 patients included in this study, 73 eyes (68.2%) underwent 1 and 34 eyes (31.8%) underwent 2 autologous CLET procedures. At a mean follow-up of 3.4 years, 50 eyes (46.7%) achieved completely epithelialized, avascular, and stable ocular surfaces. At the final visit, 58 eyes (54.2%) had improvement in visual acuity of 0.2 or more logMAR units. CONCLUSIONS Autologous CLET was successful in restoring the ocular surface and improving vision in almost half of the children blinded by ocular burns.

Accuracy of intraocular lens power calculation formulae in children less than two years.

PURPOSE To assess the accuracy of IOL power calculation formulae in children less than 2 years of age. DESIGN Retrospective, comparative study, comprising of 128 eyes of 84 children. METHODS We analyzed records of children less than 2 years with congenital cataract who underwent primary IOL implantation. Data were analyzed for prediction error using the 4 commonly used IOL power calculation formulae. We calculated the absolute prediction error with each of the formulae and the formula that gave least variability was determined. The formula that gave the best prediction error was determined. RESULTS Mean age at surgery was 11.7 ± 6.2 months. Absolute prediction error was found to be 2.27 ± 1.69 diopters (D) with SRK II, 3.23 ± 2.24 D with SRK T, 3.62 ± 2.42 D with Holladay, and 4.61 ± 3.12 D with Hoffer Q. The number of eyes with absolute prediction error within 0.5 D was 27 (21.1%) with SRK II, 8 (6.3%) with SRK T, 12 (9.4%) with Holladay, and 5 (3.9%) with Hoffer Q. Comparison between different formulae showed that the absolute prediction error with SRK II formula was significantly better than with other formulae (P < .001). Prediction error with SRK II formula was not affected by any factor such as age (P = .31), keratometry (P = .32), and axial length (P = .27) of the patient. Axial length influenced the absolute prediction error with Holladay (P = .05) and Hoffer Q formulae (P = .002). Mean keratometry influenced prediction error (P = .03) with SRK T formula. CONCLUSION Although absolute prediction error tends to remain high with all present IOL power calculation formulae, SRK II was the most predictable formula in our series.

Sensitive periods for the functional specialization of the neural system for human face processing

Significance Sensitive periods in human functional brain development were tested in humans who had been blind from birth and whose sight was restored as long as 14 y later. In investigating this rare population, our data demonstrate a general principle of brain development: rather than being born with highly specialized neural systems (e.g., for specific object categories such as faces), the functional differentiation of neural circuits seems to depend on early (visual) experience involving a decrease in responsiveness to certain events during sensitive periods. The functional tuning of neural systems seems necessary to achieve high processing proficiency. The aim of the study was to identify possible sensitive phases in the development of the processing system for human faces. We tested the neural processing of faces in 11 humans who had been blind from birth and had undergone cataract surgery between 2 mo and 14 y of age. Pictures of faces and houses, scrambled versions of these pictures, and pictures of butterflies were presented while event-related potentials were recorded. Participants had to respond to the pictures of butterflies (targets) only. All participants, even those who had been blind from birth for several years, were able to categorize the pictures and to detect the targets. In healthy controls and in a group of visually impaired individuals with a history of developmental or incomplete congenital cataracts, the well-known enhancement of the N170 (negative peak around 170 ms) event-related potential to faces emerged, but a face-sensitive response was not observed in humans with a history of congenital dense cataracts. By contrast, this group showed a similar N170 response to all visual stimuli, which was indistinguishable from the N170 response to faces in the controls. The face-sensitive N170 response has been associated with the structural encoding of faces. Therefore, these data provide evidence for the hypothesis that the functional differentiation of category-specific neural representations in humans, presumably involving the elaboration of inhibitory circuits, is dependent on experience and linked to a sensitive period. Such functional specialization of neural systems seems necessary to archive high processing proficiency.

Partial recovery of visual-spatial remapping of touch after restoring vision in a congenitally blind man.

In an initial processing step, sensory events are encoded in modality specific representations in the brain but seem to be automatically remapped into a supra-modal, presumably visual-external frame of reference. To test whether there is a sensitive phase in the first years of life during which visual input is crucial for the acquisition of this remapping process, we tested a single case of a congenitally blind man whose sight was restored after the age of two years. HS performed a tactile temporal order judgment task (TOJ) which required judging the temporal order of two tactile stimuli, one presented to each index finger. In addition, a visual-tactile cross-modal congruency task was run, in which spatially congruent and spatially incongruent visual distractor stimuli were presented together with tactile stimuli. The tactile stimuli had to be localized. Both tasks were performed with an uncrossed and a crossed hand posture. Similar to congenitally blind individuals HS did not show a crossing effect in the tactile TOJ task suggesting an anatomical rather than visual-external coding of touch. In the visual-tactile task, however, external remapping of touch was observed though incomplete compared to sighted controls. These data support the hypothesis of a sensitive phase for the acquisition of an automatic use of visual-spatial representations for coding tactile input. Nonetheless, these representations seem to be acquired to some extent after the end of congenital blindness but seem to be recruited only in the context of visual stimuli and are used with a reduced efficiency.

Duane Retraction Syndrome: Series of 441 Cases

PURPOSE To determine the demographic and clinical profile of various subtypes of Duane retraction syndrome (DRS). METHODS Retrospective case series of 441 patients. RESULTS Of the total 441 patients, 389 (88.2%) and 52 (11.8%) patients had unilateral and bilateral involvement, respectively. In both unilateral and bilateral cases, type I was the most common subtype, followed by types III and II. Mean age of presentation of type I DRS was significantly less (13.3 years) compared with types II (23 years) and III (21.9 years) (P < .05). Unilateral disease was significantly more common in females (57. 6%, P = .006), whereas there was no gender predilection in bilateral cases (P = .77). Type 1 DRS was significantly more common among females (57.96%, P = .003) compared with males, whereas there was no such gender predilection in types II and III. The left eye was more commonly involved in patients with types I and III (P < .05), whereas in type II there was no such predilection for any eye involvement. Esotropia was more common in patients with bilateral disease (53.8%) and exotropia was predominant ocular deviation in patients with types II and III (70% and 66.67%, P = .03). There was no difference in the type of deviation in patients with type I (P > .05). Upshoots and downshoots were more common in unilateral disease and types I and III compared with type II. CONCLUSION Unilateral and bilateral DRS show considerable differences in gender distribution, associated ocular deviation, overshoots, and ocular and systemic associations.

Use of the Delphi process in paediatric cataract management

Purpose To identify areas of consensus and disagreement in the management of paediatric cataract using a modified Delphi approach among individuals recognised for publishing in this field. Design A modified Delphi method. Participants International paediatric cataract experts with a publishing record in paediatric cataract management. Methods The process consisted of three rounds of anonymous electronic questionnaires followed by a face-to-face meeting, followed by a fourth anonymous electronic questionnaire. The executive committee created questions to be used for the electronic questionnaires. Questions were designed to have unit-based, multiple choice or true–false answers. The questionnaire included issues related to the preoperative, intraoperative and postoperative management of paediatric cataract. Main outcome measure Consensus based on 85% of panellists being in agreement for electronic questionnaires or 80% for the face-to-face meeting, and near consensus based on 70%. Results Sixteen of 22 invited paediatric cataract surgeons agreed to participate. We arrived at consensus or near consensus for 85/108 (78.7%) questions and non-consensus for the remaining 23 (21.3%) questions. Conclusions Those questions where consensus was not reached highlight areas of either poor evidence or contradicting evidence, and may help investigators identify possible research questions.

Safety profile of primary intraocular lens implantation in children below 2 years of age

Aim To study the safety profile of primary intraocular lens (IOL) implantation in children below 2 years of age Methods Retrospective, non-comparative, consecutive and interventional clinical case series of all patients who underwent surgery between January 2006 and December 2007. Results The data were collected for 120 eyes of 80 children with congenital/developmental cataract with a mean follow-up of 8.85±7.73 months (median 6, range 3–40). The age ranged from 1 to 23 months (mean 11.21±5.90 months, median 10 months). 31 eyes were operated on before the age of 6 months, and 89 were operated on after 6 months of age. The axial length of children ranged from 16.27 mm to 25.65 mm (mean 19.84±1.71, median 19.65). The IOL power implanted in these children ranged from 11 D to 30 D (mean 24.51±4.06 D, median 25.00). 30 eyes were implanted with rigid polymethylmethacrylate lenses, and the remaining 90 received acrylic hydrophobic foldable lenses. 8 eyes (6.7%) developed opacification of the visual axis, decentration of IOL was noticed in 2 (1.7%), increased anterior chamber inflammation was observed in five eyes (4.2%) in the early postoperative period, pigment dispersion on IOL was seen in four eyes (3.3%), and posterior synechiae were noticed in five eyes (4.2%). None of the children developed glaucoma; nor were there any endophthalmitis and retinal detachment at the last follow-up. There was no difference in terms of complications in children younger than 6 months and older than 6 months. Conclusion The results suggest that implantation of IOL in children below 2 years of age is safe and can be considered as a viable option for their visual rehabilitation.

Comparison of augmented superior rectus transposition with medial rectus recession for surgical management of esotropic Duane retraction syndrome.

BACKGROUND Medial rectus recession (MRc) and vertical rectus transpositions are procedures used to treat esotropic Duane retraction syndrome. Recently superior rectus transposition (SRT) combined with MRc has also been shown to improve primary alignment and abduction. The purpose of this study is to compare the results of augmented (ie, with scleral fixation) SRT with or without MRc with either unilateral or bilateral MRc for treatment of esotropic Duane syndrome. METHODS The medical records of patients who underwent surgery for esotropic Duane syndrome between May 2007 and February 2013 were retrospectively reviewed. Success was defined as alignment within 8(Δ) of orthotropia and abnormal head posture of <5°. RESULTS There were 8 patients in the SRT group (6 of whom had additional ipsilateral MRc) and 13 in the MRc group (6 unilateral and 7 bilateral). In the SRT group, the mean preoperative deviation was 20(Δ) of esotropia; the mean postoperative deviation, 3(Δ). In the MRc group, the mean preoperative deviation was 24(Δ) of esotropia; the mean postoperative deviation, 4(Δ). The success rate was 87% in the SRT group; 77%, in MRc group (P = 0.98). Mean abduction limitation improved from -3.6 to -2.4 units in the SRT group and from -3.6 to -3.3 units in the MRc group (P = 0.003). Induced vertical deviation or subjective torsion was not seen. Three patients in each group developed adduction limitation postoperatively. CONCLUSIONS Although both the procedures successfully correct esotropia in Duane syndrome, SRT with or without MRc has the additional advantage of improving abduction.

Contribution of muscle biopsy and genetics to the diagnosis of chronic progressive external opthalmoplegia of mitochondrial origin

Chronic progressive external opthalmoplegia (CPEO) is the most common phenotypic syndrome of the mitochondrial myopathies. Muscle biopsy, which provides important morphological clues for the diagnosis of mitochondrial disorders, is normal in approximately 25% of patients with CPEO, thus necessitating molecular genetic analysis for more accurate diagnosis. We aimed to study the utility of various histochemical stains in the diagnosis of CPEO on muscle biopsy and to correlate these results with genetic studies. Between May 2005 and November 2007 all 45 patients diagnosed with CPEO were included in the study (23 males; mean age at presentation, 35 years). Thirty-nine patients had CPEO only and six had CPEO plus; two had a positive family history but the remaining 39 patients had sporadic CPEO. Muscle biopsy samples were stained with hematoxylin and eosin, modified Gomoris trichrome stain, succinic dehydrogenase (SDH), cytochrome C oxidase (COX) and combined COX-SDH. Ragged red fibers were seen in 27 biopsies; seven showed characteristics of neurogenic atrophy only, and 11 were normal. The abnormal fibers were best identified on COX-SDH stain. A complete mitochondrial genome was amplified in muscle and blood samples of all patients. Mutations were found in transfer RNA, ribosomal RNA, ND, CYTB, COX I, II and III genes. Mitochondrial gene mutations were found in ten of the 11 patients with a normal muscle biopsy. The genetic mutations were classified according to their significance. The observed muscle biopsy findings were correlated with genetic mutations noted. Histological studies should be combined with genetic studies for the definitive diagnosis of CPEO syndrome.

Silicone band loop myopexy in the treatment of myopic strabismus fixus: surgical outcome of a novel modification

Aim To evaluate safety profile and surgical outcomes of a novel modification of loop myopexy with silicone band for myopic strabismus fixus (MSF). Design Retrospective interventional case series. Methods A retrospective chart review of patients who underwent silicone band loop myopexy between January 2008 and December 2012 for MSF at a tertiary eye care centre was undertaken. A minimum of 2 months of follow-up after surgery was required for inclusion. Patients who underwent conventional suture loop myopexy and cases with incomplete details pertaining to the preoperative alignment and movement restriction were excluded. The main outcome measures were improvement in alignment postoperatively, improvement in extra-ocular motility postoperatively, and intraoperative and postoperative complications. Results 26 eyes of 15 patients (male (9):female (6)=1.5:1) underwent silicone band loop myopexy at a mean age of 27.8±16.4 years (range 7–72 years). Mean follow-up was 7.9±8.4 months (range 2–28 months, and median 4 months). 11 patients underwent bilateral loop myopexy whereas four patients underwent unilateral loop myopexy. 16 eyes underwent additional medial rectus (MR) recession. At the last follow-up, mean abduction limitation improved to −1.5±1.3 from −2.9±1.2, p=0.0000; mean elevation limitation improved to −1.2±0.9 from −2.8±1.1, p=0.0000; mean esotropia improved to 16.9±17.4 prism dioptres (PD) from 79.3±32.3PD, p=0.0000; and success (deviation ≤20PD) was achieved in 73% (95% CI 48 to 89%). Mean hypotropia at presentation was 8.9±10.1PD (range 0–25PD), which improved to 0.6±1.3PD (range 0–4PD), p=0.007. Conclusions Modified scleral fixated silicone band loop myopexy with or without MR recession is a safe and effective procedure in the management of MSF and improves alignment significantly.