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There is a certain failure rate in traditional glaucoma surgery because of the lack of depth information in microscope images. In this work, we present a digital microscope-integrated optical coherence tomography (MIOCT) system and several custom-made OCT-compatible instruments for glaucoma surgery. Sixteen ophthalmologists were asked to perform trabeculectomy and canaloplasty on live porcine eyes using the system and instruments. After surgery, a subjective feedback survey about the user experience was taken. The experiment results showed that our system can help surgeons easily locate important tissue structures during surgery. The custom-made instruments also solved the shadowing problem in OCT imaging. Surgeons preferred to use the system in their future practice. [ABSTRACT FROM AUTHOR]

We describe a technique using a mirrored contact lens in conjunction with microscope-integrated optical coherence tomography to image peripheral retinal structures and pathology, intraoperatively. Background/Purpose: Visualization of peripheral retinal structures with optical coherence tomography (OCT) can be challenging but can offer valuable clinical information. We describe a method for intraoperative OCT of the peripheral retina. Methods: An investigational microscope-integrated OCT system with real-time 4D volumetric imaging was used in conjunction with a Goldmann style mirrored contact lens intraoperatively to capture peripheral images in three patients. Results: We identified retinoschisis, a retinal break, and areas of focal retinal detachment using our peripheral OCT method. Conclusion: Use of a Goldmann lens in conjunction with intraoperative OCT offers surgeons the ability to resolve peripheral pathology that cannot be easily evaluated with OCT otherwise. [ABSTRACT FROM AUTHOR]

Ritu Nagpal, Chetan Shakkarwal, Rinky Agarwal, Rahul Kumar Bafna, Prafulla Kumar Maharana, Namrata Sharma Cataract, Cornea & Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, IndiaCorrespondence: Namrata SharmaCataract, Cornea & Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, IndiaTel +91-11-26593144Email namrata.sharma@gmail.comPurpose: To quantitatively analyze the dimensions of the gap between the intraocular lens (IOL) and the posterior capsule using microscope-integrated optical coherence tomography (MIOCT).Setting: Institutional.Design: Prospective, interventional.Methods: A total of 105 eyes of 105 consecutive patients planned for phacoemulsification with IOL implantation were enrolled. At the end of surgery, the gap between the IOL and the posterior capsule (IOL-PC gap) was measured using MIOCT (RESCAN). The same gap was reassessed at 1 week follow-up visit using the Visante-OCT system. The cases were sub-grouped based on the grade of cataract, IOL material, size and design and were analyzed to look for any difference in the IOL-PC gap both intraoperatively and postoperatively.Results: The IOL-PC gap could be successfully measured intra-operatively in all cases, using the RESCAN. The mean gap at the end of phacoemulsification was 385.08± 264.58 μm, and at one week follow up this was 120.83± 95.13 μm.Conclusion: MIOCT may be successfully used to quantify the dimensions of the gap between the IOL and the posterior capsule. It can be used as a potential tool to further understand the dynamics of the IOL-PC space and to assess the impact of various IOL and non-IOL parameters implicated in the causation of posterior capsule opacification.Keywords: cataract surgery, intraocular lens-posterior capsule gap, microscope-integrated optical coherence tomography, spectral domain optical coherence tomography, RESCAN

Intraoperative optical coherence tomography (iOCT) is a noninvasive imaging technique that gives real-time dynamic feedback on surgical procedures. iOCT was first employed in vitreoretinal surgery, but successively served as a guidance in several anterior segment surgical approaches: keratoplasty, implantable Collamer lens (ICL) implantation, and cataract surgery. Among all of those approaches, the unbeatable features of iOCT are fully exploited in anterior and posterior lamellar keratoplasty, and the purpose of this review is to focus on the advantages and shortfalls of iOCT in these techniques, in order to assess whether this technology could be a real step forward. In deep anterior lamellar keratoplasty (DALK), iOCT is useful to evaluate the needle depth into the corneal stroma, the big bubble dissection plane, and residual stromal bed, thus aiding the standardization of the technique and the reduction of failures. In Descemet stripping automated endothelial keratoplasty (DSAEK), iOCT allowed for clear visibility of fluid at the graft/host interface, allowing for immediate rescue maneuvers and granting the best graft apposition. In Descemet membrane endothelial keratoplasty (DMEK), iOCT can track the lenticule unfolding in real time and assess graft orientation even in severe hazy corneas, thus optimizing surgical times, as well as avoiding the use of potentially hazardous exterior markers (such as the "S" stamp) and preventing unnecessary manipulation of the graft. Overall, the role of iOCT appeared crucial in several complicated cases, overcoming the difficulties of poor visualization in a fast, non-invasive way, thus raising this approach as possible gold standard for challenging conditions. Further improvements in the technology may enable autonomous centering and tracking, overcoming the current constraint of instrument-induced shadowing. [ABSTRACT FROM AUTHOR]

Intraoperative optical coherence tomography (iOCT) is a noninvasive imaging modality that provides a real-time dynamic feedback of the various surgical steps. Comprehensive literature search was performed in MEDLINE using “intraoperative optical coherence tomography” and “iOCT” as keywords. The use of iOCT as an aid to decision-making has been successfully reported in cases undergoing keratoplasty, implantable Collamer lens (ICL) implantation as well as cataract surgery. iOCT helps to assess the graft-host relationship in penetrating keratoplasty. It helps confirm the presence of a big bubble, detect subclinical big bubbles and guide layer by layer stromal dissection in cases of deep anterior lamellar keratoplasty. It acts as a guide during crucial surgical steps in endothelial keratoplasty, right from scoring of the Descemet membrane to ensuring graft apposition at the end of surgery. The morphological features of the corneal incision in phacoemulsification may be assessed. iOCT is a useful tool in assessing the status of the posterior capsule and may help identify preexisting posterior capsular defects during cataract surgery in various clinical scenarios such as posterior polar cataract, traumatic cataract, and vitrectomized eyes. It allows on-table assessment of the ICL vault and potentially facilitates exchange of ICL in the same sitting in extremes of vault. Ocular surface disorders such as ocular surface squamous neoplasia, pterygium, and dermoid may find an application for iOCT, wherein an iOCT-guided stromal dissection will ensure adequate depth of dissection. Further technological advancements may allow for automatic centration and tracking and address the present limitation of instrument-induced shadowing.

Purpose: To report the impact of transient, self-resolving, untreated "macular edema" detected on spectral domain optical coherence tomography in Asian Indian premature infants with retinopathy of prematurity (ROP) on visual acuity (VA) and refraction at 1-year of corrected age. Materials and Methods: Visual acuity and refraction of 11 infants with bilateral macular edema (Group A) was compared with gestational age-matched 16 infants with ROP without edema (Group B) and 17 preterms infants without ROP and without edema (Group C) at 3, 6, 9 and 12 months of corrected age using Teller Acuity Cards and cycloplegic retinoscopy. Sub-group analysis of the previously described pattern A and B macular edema was performed. Results: Visual acuity was lower in infants with macular edema compared with the other two control groups throughout the study period, but statistically significant only at 3 months. Visual improvement in these infants was highest between the 3 rd and 6 th month and plateaued by the end of the 1 st year with acuity comparable to the other two groups. The edema cohort was more hyperopic compared to the other two groups between 3 and 12 months of age. Pattern A edema had worse VA compared to pattern B, although not statistically significant. Conclusion: Macular edema, although transient, caused reduced VA as early as 3 months of corrected age in Asian Indian premature infants weighing

Aim: To assess the variations in cone mosaic in myopia and its correlation with axial length (AL). Subjects and Methods: Twenty-five healthy myopic volunteers underwent assessment of photoreceptors using adaptive optics retinal camera at 2° and 3° from the foveal center in four quadrants superior, inferior, temporal and nasal. Data was analyzed using SPSS version 17 (IBM). Multivariable regression analysis was conducted to study the relation between cone density and AL, quadrant around the fovea and eccentricity from the fovea. Results: The mean cone density was significantly lower as the eccentricity increased from 2° from the fovea to 3° (18,560 ± 5455-16,404 ± 4494/mm 2 respectively). There was also a statistically significant difference between four quadrants around the fovea. The correlation of cone density and spacing with AL showed that there was a significant inverse relation of AL with the cone density. Conclusion: In myopic patients with good visual acuity cone density around the fovea depends on the quadrant, distance from the fovea as well as the AL. The strength of the relation of AL with cone density depends on the quadrant and distance.

Purpose: To evaluate the predictability of the refractive correction achieved with a positional accommodating intraocular lenses (IOL) and to develop a potential optimization of it by minimizing the error associated with the keratometric estimation of the corneal power and by developing a predictive formula for the effective lens position (ELP). Materials and Methods: Clinical data from 25 eyes of 14 patients (age range, 52-77 years) and undergoing cataract surgery with implantation of the accommodating IOL Crystalens HD (Bausch and Lomb) were retrospectively reviewed. In all cases, the calculation of an adjusted IOL power (P IOLadj ) based on Gaussian optics considering the residual refractive error was done using a variable keratometric index value (n kadj ) for corneal power estimation with and without using an estimation algorithm for ELP obtained by multiple regression analysis (ELP adj ). P IOLadj was compared to the real IOL power implanted (P IOLReal , calculated with the SRK-T formula) and also to the values estimated by the Haigis, HofferQ, and Holladay I formulas. Results: No statistically significant differences were found between P IOLReal and P IOLadj when ELP adj was used (P = 0.10), with a range of agreement between calculations of 1.23 D. In contrast, P IOLReal was significantly higher when compared to P IOLadj without using ELP adj and also compared to the values estimated by the other formulas. Conclusions: Predictable refractive outcomes can be obtained with the accommodating IOL Crystalens HD using a variable keratometric index for corneal power estimation and by estimating ELP with an algorithm dependent on anatomical factors and age.

Purpose: To correlate the structural and functional changes following intravitreal injection of dexamethasone 0.7 mg (Ozurdex ® ) implant in patients with recalcitrant uveitic cystoid macular edema (CME). Materials and Methods: In a prospective, interventional, nonrandomized study, 30 eyes (27 patients) with uveitic CME received Ozurdex ® implant and were followed-up for 24 weeks at periodic intervals to monitor structural alterations seen on spectral domain optical coherence tomography (SD-OCT). The outcome measures included change in central macular thickness (CMT) and best-corrected visual acuity (BCVA) as well as structural alterations seen on OCT such as change in the height of cystoid spaces (CSs) and sub-foveal serous retinal detachment (SSRD). The integrity of external limiting membrane and inner-outer segment junction was assessed at baseline and follow-up visits. Results: Mean age of the patients was 46.09 ± 15.66 years. The mean CMT decreased by 96 μm at 1-day, 231.64 μm at 1-week, 254.21 μm at 4 weeks and 249.14 μm at 12 weeks (P < 0.001) compared with baseline. BCVA improved from a baseline mean of 0.62 LogMAR units to 0.49 on day 1 to 0.31 at 24 weeks (P < 0.001). A decrease in the mean height of CS, that is, 133.28 μm from a baseline of 317.71 μm was noted on the 1 st day (P < 0.001). 4 eyes demonstrated the presence of CS at 4 weeks, 1 eye at 6 weeks and 3 eyes at 12 weeks. At baseline, 16 eyes (53.33%) demonstrated the presence of SSRD. Among these, 11 eyes showed resolution of SSRD on day 1. SSRD resolved in all patients at 4 weeks and was maintained up to 24 weeks. Conclusions: Ozurdex ® implant improves the visual outcome of patients with recalcitrant uveitic CME. Reversibility of retinal changes may be possible following treatment with dexamethasone implant. Thus final visual outcome may be independent of pretreatment CMT, the height of CS or SSRD.

Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications.

Purpose: To measure the choroidal thickness (CT) after dynamic exercise by using enhanced depth imaging optical coherence tomography (EDI-OCT). Materials and Methods: A total of 19 healthy participants performed 10 min of low-impact, moderate-intensity exercise (i.e., riding a bicycle ergometer) and were examined with EDI-OCT. Each participant was scanned before exercise and afterward at 5 min and 15 min. CT measurement was taken at the fovea and 1000 μ away from the fovea in the nasal, temporal, superior, and inferior regions. Retinal thickness, intraocular pressure, ocular perfusion pressure (OPP), heart rate, and mean blood pressure (mBP) were also measured. Results: A significant increase occurred in OPP and mBP at 5 min and 15 min following exercise (P ˂ 0.05). The mean subfoveal CT at baseline was 344.00 ± 64.71 μm compared to 370.63 ± 66.87 μm at 5 min and 345.31 ± 63.58 μm at 15 min after exercise. CT measurements at all locations significantly increased at 5 min following exercise compared to the baseline (P ˂ 0.001), while measurements at 15 min following exercise did not significant differ compared to the baseline (P ˃ 0.05). There was no significant difference in retinal thickness at any location before and at 5 min and 15 min following exercise (P ˃ 0.05). Conclusion: Findings revealed that dynamic exercise causes a significant increase in CT for at least 5 min following exercise.

Optical coherence tomography (OCT) has revolutionized imaging of ocular structures and various disease conditions. Though it has been used in the clinic for some decades, the OCT has only recently found its way into the operating theater. Early attempts at intraoperative OCT, hand-held and microscope mounted, have already improved our understanding of the surgical pathology and the role it might play in surgical decision-making. The microscope-integrated OCT now allows seamless, high-resolution, real-time imaging of surgical maneuvers from the incision to wound closure. Visualization of instruments and intraoperative tissue manipulation are possible with this in vivo modality and, therefore, help improve the outcome of surgery. In this article, we describe the advantages it offers during various vitreoretinal procedures.

ExPress glaucoma filtration device (GFD) has recently become available in India as a surgical option for glaucoma patients. We retrospectively evaluated the outcome of ExPress GFD in 12 eyes with advanced glaucoma with intraocular pressures (IOPs) not controlled on maximal tolerable medical therapy. The mean preoperative IOP of 29.58 ± 7.13 mmHg decreased to 17.0 ± 2.67 and 17.40 ± 0.89 mmHg at 6 and 12 months after surgery. Absolute success (IOP ≤ 18 mmHg, with no additional glaucoma medications) was achieved in eight cases (66.7%) and qualified success (IOP ≤ 18 mmHg, with additional glaucoma medications) in two cases (16.7%) at 1-year after surgery. Early intervention was needed in 4 patients; two underwent anterior chamber reformation while the other two required needling. Two patients required resurgery. There was no significant change in the best corrected visual acuity postoperatively (P = 0.37). ExPress GFD does not seem to offer a benefit over standard trabeculectomy in patients with advanced glaucomatous disease in terms of IOP control or complication rate. However, due to the small sample size with a heterogeneous mixture of primary and secondary glaucoma′s, we await further studies with a larger sample size and long-term follow-up, to see how the device performs.

Aim: The aim of the present study was to study the effect of ocular magnification on macular measurements made using spectral domain optical coherence tomography (OCT). Materials and Methods: One hundred and fifty-one subjects were included from the normative study of foveal morphology carried out at our hospital. Subjects underwent comprehensive eye examination and macular scanning using Cirrus high-definition OCT and axial length (AXL) measurement. Macular cube 512 × 128 scan protocol was used for scanning the macula. Automated measurements of the fovea namely foveal diameter, foveal slope (lateral measurements) and foveal depth (axial measurement) were taken. A correction factor for ocular magnification was done using the formula t = p × q × s, where "t0" is the corrected measurement, "p" is the magnification of OCT, "q0" is the ocular magnification, and "s" is the measurement on OCT without correction. The difference between corrected and uncorrected measurements was evaluated for statistical significance. Results: Mean AXL was 22.95 ± 0.78 mm. Refractive error ranged from −3D to +4D. Mean difference between measured and corrected foveal diameter, slope and depth was 166.05 ± 95.37 ΅m (P < 0.001), 0.81° ± 0.53° (P < 0.001) and 0.05 ± 0.49 ΅m (P = 0.178) respectively. AXL lesser than the OCT calibrated value of 24.46 mm showed an increased foveal diameter (r = 0.961, P < 0.001) and a reduced foveal slope (r = −0.863, P < 0.001) than the corrected value. Conclusion: Lateral measurements made on OCT varied with AXL s other than the OCT calibrated value of 24.46 mm. Therefore, to estimate the actual dimensions of a retinal lesion using OCT, especially lateral dimensions, we recommend correction for the ocular magnification factor.

A professional mountain trekker presented with gradual, moderate visual decline in one eye. The subnormal vision could not be explained by the examination of anterior and posterior segment of either eye, which was unremarkable. Optical coherence tomography and autofluorescence imaging revealed subtle defects in the outer retina, which correlated with the extent of visual disturbance. A novel presentation of retinal phototoxicity due to indirect solar radiation reflected from snow in inadequately protected eyes of a chronically exposed subject is reported.

A 36-year-old lady presented with redness and decreased vision in right eye since 6 months. She was earlier diagnosed of cavitary lung lesion, presumed secondary to tuberculosis and treated with anti-tubercular treatment for 4 months. Examination of affected right eye revealed nil light perception, conjunctival congestion with an exuberant mass in the inferotemporal bulbar conjunctiva, proptosis, iris neovascularization, 360° closed angles, intraocular pressure of 48 mm Hg, exudative retinal detachment, uveal mass and orbital extension. A diagnostic needle biopsy of uveal mass revealed malignant cells. Computed tomography-guided lung biopsy revealed squamous cell carcinoma (SCC), indicating metastatic spread from the orbit. She underwent lid-sparing exenteration of the right eye. Histopathological examination of the orbital tissue revealed mucoepidermoid carcinoma arising from the conjunctiva with extensive invasion into the orbital tissue, muscle fibers, sclera, choroid and optic nerve. Multiple tumor emboli were seen in the lumen of orbital blood vessels. In conclusion, mucoepidermoid carcinoma of the conjunctiva is a rare, aggressive variant of SCC. Early intervention is essential to prevent intraocular invasion and systemic metastasis.

Choroidal osteoma is a usually unilateral benign tumor of the choroid composed of mature bone. Optical coherence tomography (OCT) has been used to image osteoma for several years. With the advent of enhanced depth imaging (EDI) feature of spectral-domain OCT (SD-OCT), better visualization of the morphology of choroidal lesions has been possible. Herein we present a case of choroidal osteoma in a 45-year-old woman, wherein in vivo morphology of the choroidal osteoma had been visualized using EDI technique of SD-OCT before and after performing photodynamic therapy. EDI OCT has proven to be a valuable noninvasive imaging modality, almost comparable to histopathological examination, for diagnosing choroidal osteomas and for providing an insight into the in vivo micromorphological changes occurring during the course of the disease.

Intraoperative optical coherence tomography (iOCT) is a noninvasive imaging modality that provides a real-time dynamic feedback of the various surgical steps. Comprehensive literature search was performed in MEDLINE using "intraoperative optical coherence tomography" and "iOCT" as keywords. The use of iOCT as an aid to decision-making has been successfully reported in cases undergoing keratoplasty, implantable Collamer lens (ICL) implantation as well as cataract surgery. iOCT helps to assess the graft-host relationship in penetrating keratoplasty. It helps confirm the presence of a big bubble, detect subclinical big bubbles and guide layer by layer stromal dissection in cases of deep anterior lamellar keratoplasty. It acts as a guide during crucial surgical steps in endothelial keratoplasty, right from scoring of the Descemet membrane to ensuring graft apposition at the end of surgery. The morphological features of the corneal incision in phacoemulsification may be assessed. iOCT is a useful tool in assessing the status of the posterior capsule and may help identify preexisting posterior capsular defects during cataract surgery in various clinical scenarios such as posterior polar cataract, traumatic cataract, and vitrectomized eyes. It allows on-table assessment of the ICL vault and potentially facilitates exchange of ICL in the same sitting in extremes of vault. Ocular surface disorders such as ocular surface squamous neoplasia, pterygium, and dermoid may find an application for iOCT, wherein an iOCT-guided stromal dissection will ensure adequate depth of dissection. Further technological advancements may allow for automatic centration and tracking and address the present limitation of instrument-induced shadowing. [ABSTRACT FROM AUTHOR]

Optical coherence tomography (OCT) has revolutionized imaging of ocular structures and various disease conditions. Though it has been used in the clinic for some decades, the OCT has only recently found its way into the operating theater. Early attempts at intraoperative OCT, hand-held and microscope mounted, have already improved our understanding of the surgical pathology and the role it might play in surgical decision-making. The microscope-integrated OCT now allows seamless, high-resolution, real-time imaging of surgical maneuvers from the incision to wound closure. Visualization of instruments and intraoperative tissue manipulation are possible with this in vivo modality and, therefore, help improve the outcome of surgery. In this article, we describe the advantages it offers during various vitreoretinal procedures. [ABSTRACT FROM AUTHOR]

Central reading centers (CRCs) have several crucial roles in the conduct of clinical trials, providing key input during the study design, preparation of the operations manual, as well as site and photographer certification. They provide objective, standardized grading of images from study subjects, which determines study eligibility, and also evaluate lesion features at subsequent study visits. CRCs need to adhere strictly to Good Clinical Practice (GCP) guidelines, as well as the established standard operating procedures in order to ensure that images are graded properly. The role of CRCs will continue to evolve, and include the use of web-based image transmission and grading platforms.

Rhinosporidiosis is a rare infection caused by Rhinosporidium seeberi, an organism classified in its own class, mesomycetozoea. It commonly affects mucus membranes namely the nasal mucosa, pharynx and the conjunctiva. We present the case of an 8-year-old female who presented with a flat, red, vascular, fleshy, pedunculated mass arising from the tarsal conjunctiva of the right upper eyelid. The mass was completely excised. On histopathological examination, multiple sporangia were seen in various stages of degeneration, consistent with rhinosporidiosis. The diagnosis of rhinosporidiosis is based solely on its microscopic features, and the treatment is surgical excision. This condition is endemic in the temperate regions of the Indian subcontinent, but it has been known to occur even in the colder regions of North America and Eastern Europe. Although a rare clinical entity, the possibility of rhinosporidiosis must be borne in mind when evaluating any polypoidal conjunctival mass.