Repeatability of Choroidal Thickness Measurements in Healthy Subjects using RTVue XR Optical Coherence Tomography.

Purpose: To determine the intrasession, intraobserver, interobserver, and repeatability of choroidal thickness measurements in the healthy subjects imaged on enhanced depth imaging system of RTVue XR spectral domain optical coherence tomography (OCT). Methods: In this prospective, cross-sectional study, seventy eyes of 70 healthy volunteers with no known ocular disease were imaged using high-density scanning protocol of RTVue XR OCT. In a single imaging session, three sequential 12 mm macular-enhanced depth horizontal line scans were obtained through the fovea. Two experienced examiners measured the subfoveal choroidal thickness (SFCT), choroidal thickness at 500 µm nasally and temporally from the fovea in all the eyes, using the manual calipers provided in the software. The graders were masked to each other's measurement readings. The coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were used to measure the reliability within graders. Intergrader variability was assessed using Bland-Altman method and 95% limits of agreement (LoA). Results: Intragrader CR for grader one was 4.11 µm (95% confidence interval [CI], -2.84-11.06) for SFCT and 5.73 µm (95% CI, -3.71-15.16) for the grader two. Intragrader ICC of grader one ranged from 0.996 for SFCT to 0.994 for temporal choroidal thickness. Intragrader ICC of grader two ranged from 0.993 for temporal choroidal thickness to 0.991 for SFCT. Intergrader CR ranged from 5.24 µm (95% CI, -4.66-15.15) for SFCT to 5.89 µm (95% CI, -7.27-19.04) for temporal choroidal thickness. Intergrader 95% LoA for SFCT, nasal and temporal choroidal thickness were, -15.84-12.15 µm, -15.99-17.7 µm, and - 19.12-15.57 µm, respectively. Conclusion: Choroidal thickness measurements can be quantified with good repeatability using RTVue XR OCT, which would be useful in patients with chorioretinal diseases.

Incidence of Glaucoma after Combined Descemet's Stripping Endothelial Keratoplasty and Retropupillary Fixated Iris-Claw Lens.

Purpose: To assess the incidence of glaucoma after combined Descemet's stripping endothelial keratoplasty (DSEK) and retropupillary fixated iris-claw intraocular lens (IOL) implantation in the patients with bullous keratopathy (BK) who required secondary IOL or IOL exchange. Methods: In this retrospective case series, medical records of 22 patients who underwent combined DSEK and retropupillary fixated iris-claw IOL implantation were evaluated. Preoperative vision, intraocular pressure (IOP), postoperative IOP at different time periods, and intraoperative and postoperative complications were analyzed. Results: A total of 22 eyes of 22 patients (7 females and 15 males) were analyzed. The median age was 62 years, and the median duration of the postoperative follow-up was 106.5 days. The corrected distance visual acuity improved from a median of 1.85 logMAR to 1.68 logMAR. None of the patients had intraoperative complications. Three patients (13.6%) had dislocation of the donor tissue on the 1st postoperative day and were successfully rebubbled. Six eyes (27.3%) had graft failure and required penetrating keratoplasty. Eleven eyes (50%) had a sustained rise in the IOP, of which 2 (9.09%) had ocular hypertension and 9 eyes (40.9%) progressed to glaucoma. Conclusions: DSEK combined with retropupillary fixated iris-claw lens is a good surgical option for the management of aphakic/pseudophakic BK in patients who require secondary IOL or IOL exchange. Regular IOP monitoring after the surgery is an essential, as there is a risk of IOP rise and glaucoma in the postoperative period. Clinicians should be vigilant and control the IOP to prevent glaucoma progression.

Effect of pupil size on posterior chamber phakic intraocular lens vault measurements.

PURPOSE: The aim of this study was to measure the implantable collamer lens (ICL) vault changes with anterior segment optical coherence tomography (AS-OCT) after the implantation of the Visian posterior chamber phakic ICL with a central hole (V4c) in relation to the pupil size. METHODS: This retrospective observational pilot study included 32 eyes of 16 patients, who underwent V4c ICL implantation. ICL vault was measured with AS-OCT in undilated and fully dilate state of the pupil. Primary outcome measure was the change in the vault of V4c ICL at the maximum and minimum pupil size. RESULTS: Median (IQR) undilated and post-dilated vault measurement was 393.00 (335.50-493.50) microns and 421.00 (338.50-503.75) microns, respectively, which was not statistically significant (P = 0.44). CONCLUSION: No statistically significant difference was observed between the undilated and post-dilated ICL vault measurements. Hence, the postoperative vault can be measured either in resting, undilated state or fully dilated state of the pupil and would be similar irrespective of the pupil size.

Surgically induced astigmatism and refractive outcomes following phacotrabeculectomy.

Purpose: To objectively evaluate surgically induced astigmatism (SIA) after phacotrabeculectomy using keratometry and topography and to compare the magnitude of SIA and the refractive outcomes of single-site and twin-site phacotrabeculectomies. Methods: Forty prospective subjects were enrolled in the study and were randomized into single-site and twin-site cohorts. SIA was objectively assessed using keratometry and Orbscan before and at three months after surgery. For both cohorts, the changes in SIA were assessed using power vector analysis compared at the third month after surgery. Results: Each cohort consisted of 20 eyes. The preoperative parameters and postoperative IOP were comparable and similar, respectively, in both the cohorts (P = 0.1). Majority of the patients in both the cohorts had preoperative against-the-rule (ATR) astigmatism. The median change in SIA at the three-month postoperative visit was similar in both the cohorts, with a small increase in ATR astigmatism. Although the SIA change measured by keratometry in the J0 component was similar in both the groups (P = 0.54), that of J45 was significantly different (P = 0.01). However, the median change in SIA was similar in both the groups for both the J0 (P = 0.52) and J45 components (P = 0.94) when measured by Orbscan. The SIA in both the groups measured with keratometry (P = 0.62) and topography (P = 0.52) were clinically and statistically similar. In both the groups, the refraction was similar at 1 month and 3 months. Conclusion: The SIA as measured with keratometry and topography was similar in the single-site and twin-site phacotrabeculectomy cohorts at the end of 3-months. The postoperative refraction was stabilized in 1-month in both the groups.

Echographic study of extraocular muscle thickness in normal Indian population.

PURPOSE: To establish normative data of extraocular muscle (EOM) dimensions, both vertically and horizontally, using a reproducible echographic method in various age groups. METHODS: Two hundred eyes of 100 healthy subjects (50 males and rest females) were included in this prospective observational study. All subjects were divided into 5 groups with an interval of 10 years from 10 to 60 years. Each group contained 10 male and 10 female healthy subjects. A single operator took measurements at 4 mm distance from the globe plane after drawing a perpendicular line on the globe to the muscle belly. RESULTS: The average age of subjects was 37.28 ± 17.14 years. Intraobserver reproducibility was very high (intersession concordance correlation co-efficient = 0.995). Mean horizontal and vertical diameters of recti were 3.0775 and 8.26 mm, respectively. Mean muscle thickness of superior rectus/levator palpebral superioris (LPS) muscle complex and LPS was 4.56 and 1.45 mm, respectively. Extraocular muscle diameter increases up to the middle age, then it starts decreasing. There was no statistically significant correlation between diameter of each EOM, both eye and gender (p â©¾ 0.05). There was a non-significant change in extraocular muscle thickness with age. CONCLUSION: The study provides normative data for extraocular muscle thickness in both genders of various age groups in Indian population. Muscle dimensions do not change significantly with age, between the eyes and gender.

Binocular vision of bilaterally pseudophakic eyes with induced astigmatism.

PURPOSE: Induced myopic astigmatism improves the monocular near logMAR (logarithm of the minimal angle of resolution) acuity of pseudophakes with monofocal intraocular lens implants but with a small loss in distance acuity. The impact of induced astigmatism on binocular vision of pseudophakes remains unknown. This study determined the impact of bilaterally induced astigmatism on binocular distance and near logMAR and stereoacuity of bilateral pseudophakes with monofocal intraocular lens implants. METHODS: Distance (3 m) and near (40 cm) logMAR acuity and near (40 cm) stereoacuity were measured in 15 bilateral pseudophakes with 10 different combinations of induced astigmatism. Combinations were chosen such that one eye had no astigmatism or 1 diopter (D) myopic astigmatism at 90 degrees axis or 1 D hyperopic astigmatism at 90 degrees axis. The fellow eye had the same error or that with orthogonal axis (180 degrees) or different magnitude (2.5 D) or opposite polarity. RESULTS: Distance logMAR acuity deteriorated by up to 0.2 logMAR units from median best-corrected values (-0.06 logMAR) only for bilaterally induced (p < 0.01) but not for unilaterally induced (p > 0.9) astigmatism. Near logMAR acuity and stereoacuity improved by up to 0.25 logMAR units and 130 arc sec from their respective median uncorrected values (0.65 logMAR and 225.8 arc sec) for induced myopic astigmatism (p < 0.001). Near acuity was similar or worse than uncorrected values for induced hyperopic astigmatism (p ≥ 0.003). Stereoacuity was better with parallel than with orthogonal axes of induced myopic astigmatism in the two eyes (p = 0.001). LogMAR acuity did not change with axis of astigmatism in the two eyes (p > 0.6). CONCLUSIONS: Distance and near logMAR acuity and stereoacuity of bilateral pseudophakes vary with the combination of astigmatism induced before two eyes. Combinations with myopic astigmatism partly benefit binocular near vision, albeit with a loss of distance vision. Near stereoacuity is better with parallel than with orthogonal axes of myopic astigmatism in the two eyes. Visual performance is equal to or worse than uncorrected condition for hyperopic astigmatism.

Image quality analysis of pseudophakic eyes with uncorrected astigmatism.

PURPOSE: To determine the combined impact of uncorrected astigmatism, pupil diameter, and wavefront aberrations on the distance and near visual performance of pseudophakic eyes with monofocal intraocular lens (IOL) implants using objective image quality (IQ) metrics. METHODS: Monocular distance (4 m) and near (40 cm) logMAR acuities of 15 emmetropic pseudophakic eyes were obtained without astigmatism and with 2.5 diopters myopic to 2.5 diopters hyperopic astigmatism induced along a 90-degree axis. The IQ metrics were calculated from the participant's wavefront aberrations and habitual pupil diameter for all values of astigmatism and correlated with logMAR acuity. The analysis was repeated without higher-order aberrations (HOAs) and with the entire wavefront data for 6-, 3-, and 1.5-mm pupil diameters. RESULTS: Distance acuity deteriorated with uncorrected astigmatism (p < 0.01), whereas near acuity improved with uncorrected myopic astigmatism and deteriorated with uncorrected hyperopic astigmatism (both p < 0.01). The logEW IQ metric showed the best correlation with logMAR acuity (r = 0.86). Distance logEW values deteriorated whereas near logEW values improved in the presence of HOAs for all values of uncorrected astigmatism (p < 0.01). Distance logEW values for 6- and 3-mm pupil diameters were worse than that of the 1.5-mm pupil diameter for all values of uncorrected astigmatism and for both viewing distances (p < 0.01). CONCLUSIONS: Image quality metrics analysis can be used successfully to determine the impact of uncorrected astigmatism, pupil diameter, and HOAs on the distance and near logMAR acuities of pseudophakic eyes with monofocal IOL implants. The improvement in near IQ with uncorrected myopic astigmatism and HOAs suggests that these two factors supplement each other to improve near visual performance of pseudophakic eyes. Such an improvement in near vision is however associated with a loss of distance vision in these eyes.

The precision of ophthalmic biometry using calipers.

OBJECTIVE: The purpose of the study is to determine the precision of whole globe and cornea measurements acquired using calipers, and to quantify the intraoperator and interoperator variance. DESIGN: Experimental study. PARTICIPANTS: Ten human donor eyes. METHODS: Ten human eyes (donor age, 16-54 years) were obtained between 18.5 and 66.5 hours postmortem. The horizontal and vertical diameters and the anteroposterior length of the globe were measured using a digital Vernier caliper. The horizontal and vertical diameters of the cornea were measured using both a digital Vernier caliper and a Castroviejo caliper. The measurements were performed by 3 operators with 5 repeat measurements for each dimension. RESULTS: No significant differences were observed between measurements of globe anteroposterior length, horizontal diameter, and vertical diameter. Horizontal corneal diameter was greater than vertical diameter with all instruments and all operators. Variability of either instrument did not change with measurement object scale, and was similar across all operators. No significant differences were observed between the variabilities of the 2 devices. The mean intraoperator SD was 0.127 ± 0.023 mm with the digital caliper and 0.094 ± 0.056 mm with the Castroviejo caliper. CONCLUSIONS: The precision of commercially available calipers in ophthalmic biometry measurements is limited to approximately 0.1 mm.

Relation between uncorrected astigmatism and visual acuity in pseudophakia.

PURPOSE.: The end point of astigmatic correction after cataract surgery will depend on how uncorrected astigmatism impacts distance and near vision of pseudophakic eyes. This study determined the impact of induced astigmatism and pupil size on the distance and near acuity of otherwise emmetropic pseudophakic eyes implanted with monofocal intraocular lenses. METHODS.: Monocular high-contrast distance (4 m) and near (40 cm) logMAR acuity was determined in 15 subjects (mean ± 1 SD, 57.9 ± 9.0 years) without astigmatism and with 2.5 diopters (D) myopic to 2.0 D hyperopic astigmatic lenses induced in 0.5-D steps at 0-, 45-, 90-, and 135-degree axes. This experiment was repeated for the same range of induced astigmatism with 1.5-, 3-, and 6-mm artificial pupil diameters placed before one eye of 10 subjects dilated with 10% phenylephrine HCl. RESULTS.: Distance acuity deteriorated with astigmatism for all axes tested (p < 0.01). Near acuity deteriorated with hyperopic astigmatism (p < 0.1), whereas it improved with up to 1 D of myopic astigmatism before saturating for all axes tested (p < 0.01). Distance and near acuity improved with a reduction in pupil diameter (p < 0.01). The change in distance and near acuity with induced astigmatism was smaller for 1.5-mm than for 3-mm and 6-mm pupil diameters (p < 0.01). CONCLUSIONS.: Partial restoration of near acuity with uncorrected myopic astigmatism comes with a proportional loss of distance acuity in pseudophakic eyes. Uncorrected myopic astigmatism more than 1 D results in a large loss of distance acuity at no additional benefit to near acuity. Both distance and near acuities with and without astigmatism are benefited with a reduction in pupil diameter. Uncorrected hyperopic astigmatism results in deterioration of both distance and near acuities of pseudophakic eyes.

Refractive surprise following implantation of correct powered intraocular lens--a real surprise!

We report a case of a 60-year-old male with unsatisfactory visual outcome following an uneventful phacoemulsification surgery for the left eye at our hospital. The evaluation of his anterior segment revealed a clear cornea, a well-positioned in-the-bag intraocular lens (IOL) and normal posterior segment. His vision in the left eye was 20/160 improving to 20/20 with +6.5 D Sphere. Repeat biometry of the left eye revealed IOL power of 22.0 D, which was same as the power of the IOL implanted during the cataract surgery. The patient underwent IOL explantation and implantation of another foldable IOL of 22.0 D. On follow-up he had an uncorrected visual acuity of 20/20. On evaluation with the Scheiner optical system, the explanted lens was found to have power of +13.92 D. This case highlights the rare possibility of postoperative refractory surprise due to incorrect labelling of the IOL by the manufacturer.