Estimation of Intraocular Lens Power Calculation after Myopic Corneal Refractive Surgery: Using Corneal Height in Anterior Segment Optical Coherence Tomography

PurposeTo investigate the feasibility of estimating effective lens position (ELP) and calculating intraocular lens power using corneal height (CH), as measured using anterior segment optical coherence tomography (AS-OCT), in patients who have undergone corneal refractive surgery.MethodsThis study included 23 patients (30 eyes) who have undergone myopic corneal refractive surgery and subsequent successful cataract surgery. The CH was measured with AS-OCT, and the measured ELP (ELP_m) was calculated. Intraocular lens power, which could achieve actual emmetropia (P_real), was determined with medical records. Estimated ELP (ELP_est) was back-calculated using P_real, axial length, and keratometric value through the SRK/T formula. After searching the best-fit regression formula between ELP_m and ELP_est, converted ELP and intraocular lens power (ELP_conv, P_conv) were obtained and then compared to ELP_est and P_real, respectively. The proportion of eyes within a defined error was investigated.ResultsMean CH, ELP_est, and ELP_m were 3.71 ± 0.23, 7.74 ± 1.09, 5.78 ± 0.26 mm, respectively. The ELP_m and ELP_est were linearly correlated (ELP_est = 1.841 × ELP_m - 2.018, p = 0.023, R = 0.410) and ELP_conv and P_conv agreed well with ELP_est and P_real, respectively. Eyes within ±0.5, ±1.0, ±1.5, and ±2.0 diopters of the calculated P_conv, were 23.3%, 66.6%, 83.3%, and 100.0%, respectively.ConclusionsIntraocular lens power calculation using CH measured with AS-OCT shows comparable accuracy to several conventional methods in eyes following corneal refractive surgery.     

Anterior Segment Optical Coherence Tomography

Optical coherence tomography (OCT) is a non-contact optical signal acquisition and processing device that provides magnified, high resolution cross-sectional images of ocular tissues. Development of anterior segment OCT (AS-OCT) offers the benefits of fine resolution and noninvasive examination to investigation of anterior segment anatomy to the depth of the iris plane. This imaging device has been utilized for investigation into a myriad of corneal and anterior segment disease. Recent technological advances toward three-dimensional visualization broaden the scope of AS-OCT in ophthalmologic evaluation. The AS-OCT is a valuable imaging tool whose use in research and clinical practice will continue to expand our knowledge and management of various ophthalmic conditions.     

Anterior Segment Applications of Optical Coherence Tomography Angiography

ABSTRACT

Purpose: To review the current literature regarding optical coherence tomography angiography (OCT-A) applications in the anterior segment.

Methods: A literature search was performed for terms including OCT-Angiography, anterior segment, cornea, conjunctiva, iris, applications and use in ophthalmology.

Results: Fifteen studies were identified, 14 in human subjects. Studies with OCT-A of the conjunctiva, episclera, cornea, and iris were identified, some with normal eyes imaged and others with various pathologies. Most of these studies imaged corneal neovascularization. Three studies described protocols used for image acquisition, one of which was referenced by two later papers.

Conclusions: OCT-A is a noninvasive technology with recent applications in the anterior segment. Several pilot studies have been performed on various anterior segment structures and disease states however standardization of image acquisition techniques is still needed. Future imaging could allow noninvasive and serial monitoring of pathology as well as recurrence after therapeutic intervention.     

Prevalence of Macular Abnormalities Identified Only on Optical Coherence Tomography in Korean Patients Scheduled for Cataract Surgery

PurposeTo assess the prevalence of macular abnormalities identified only on macular optical coherence tomography (OCT) which were not suspected by biomicroscopic fundus examination, and examine the clinical outcome of patients with these macular abnormalities during preoperative evaluation for cataract surgery in a large series of Korean patients.MethodsMacular OCT was performed on patients scheduled for routine cataract surgery by the same physician at Seoul St. Mary’s Hospital, between June 2018 and November 2019. The patients’ medical records were reviewed retrospectively to obtain demographic data and the results of preoperative evaluation before cataract surgery. Patients were divided into two groups based on the preoperative macular OCT results: normal and abnormal OCT groups.ResultsNine hundred eighty-seven eyes (698 patients) were included in this study. Macular OCT identified abnormalities in 44 eyes (4.5%) of 35 patients (5.0%). Twenty-one eyes (2.1%) had age-related macular degeneration, 20 eyes (2.0%) had epiretinal membrane, and three eyes (0.3%) had lamellar hole. Patients with macular abnormalities identified on macular OCT had a statistically significant higher mean age than those who had normal OCT findings (p < 0.001). Best-corrected visual acuity was worse in patients with abnormal macular OCT after cataract surgery (p = 0.048).ConclusionsIn the preoperative evaluation for cataract surgery in Korean patients, one in every 20 patients had macular abnormalities identified only on macular OCT in spite of unremarkable macular findings on biomicroscopic funduscopy. Age was significantly higher in patients with abnormal macular OCT findings. Thus, inclusion of macular OCT examination in preoperative screening before routine cataract surgery would be beneficial.     

Intraoperative Optical Coherence Tomography in Vitreoretinal Surgery

ABSTRACT

Intraoperative OCT (iOCT) is an emerging modality capable of displaying real-time OCT images to the surgeon during surgery. The use of iOCT during vitreoretinal surgery improves our understanding of the tissue alterations that occur during surgical manipulations, which may impact surgical decision-making. We review the current iOCT modalities and clinical applications of iOCT.     

Structural Analysis of Different Incision Sizes and Stromal Hydration in Cataract Surgery Using Anterior Segment Optical Coherence Tomography

Purpose

To analyze healing changes of corneal wounds of different corneal incision sizes with or without stromal hydration in cataract surgery using anterior segment optical coherence tomography.

Methods

Cataract surgeries were performed by a single surgeon and 2.2- and 2.8-mm corneal incisions were made using a diamond blade (ME-759; Meyco, Biel-Bienne, Swiss). Patients were divided into four groups according to incision size (2.2 and 2.8 mm), and with/without stromal hydration. Fifteen eyes were assigned to each group and incision wounds were measured using anterior segment optical coherence tomography at 2 hours, 1 day, 1 week, 1 month, and 3 months postoperatively. Corneal thickness, incision length and incision angle were measured and existence of epithelial, endothelial gaping and Descemet''s membrane detachment was evaluated.

Results

Incision thickness was greater in the group with stromal hydration than in the group without on operation day (p < 0.05). Stromal hydration exerted greater influence in the 2.2-mm incision group than in the 2.8-mm incision group. Corneal thickness decreased more rapidly in the stromal hydration group than in the group with no hydration (p = 0.022). Endothelial gaping was greater in the 2.2-mm incision group than in the 2.8-mm incision group 1 day, 1 month, and 3 months after surgery (p = 0.035, p = 0.009, and p = 0.008, respectively). No other statistical significance was observed between the two groups (2.2 and 2.8 mm) during follow-up regarding corneal thickness, epithelial gaping and Descemet''s membrane detachment.

Conclusions

Corneal wounds with a smaller incision could be more vulnerable to external stimuli such as stromal hydration and are less stable than those with a larger incision.     

Current and Potential Applications of Anterior Segment Optical Coherence Tomography in Contact Lens Fitting

Optical coherence tomography (OCT) is a non-invasive, high-resolution and high-speed imaging modality that has enjoyed rapid growth in ophthalmology since its development 20 years ago. Contact lens fitting is traditionally based on trial lenses, which is expensive and time-consuming. Modern anterior segment OCT is capable of generating three-dimensional ocular surface maps of the cornea and sclera with potential application in contact lens fitting. This paper reviewed the history, the ophthalmic applications, and the most recent advancement in three-dimensional anterior segment OCT. There is very limited literature of OCT in contact lens fitting to date. This review anticipates an increase in this application in the near future.     

Comparison of Central Corneal Thickness with Ultrasound Pachymetry,Noncontact Specular Microscopy and Spectral Domain Optical Coherence Tomography

Background: To determine the agreement of central corneal thickness (CCT) measurements taken with ultrasonic pachymetry (USP), spectral domain optical coherence tomography (SD-OCT) and noncontact specular microscopy (NSM).

Methods: A prospective, observational, cross-sectional study was performed in the outpatient ophthalmology clinic. CCT was measured in a total of 147 eyes of 147 consecutive healthy patients with USP, NSM, and SD-OCT. Same examiner performed all examinations. Bland–Altman plots were used to evaluate the agreement between instruments.

Results: The average CCT values obtained by USP, NSM, and SD-OCT were 555 ± 37 µm, 554 ± 34 µm, and 546 ± 34 µm, respectively. There was a strong correlation between instruments: USP with SD-OCT (r = 0.937, p < 0.01), USP with NSM (r = 0.943, p < 0.01) SD-OCT with NSM (r = 0.975, p < 0.01) for CCT. The mean differences (lower/upper limit of agreement) for CCT measurements were ?10 ± 12.9 µm (15.28/?35.28) between SD-OCT and USP, ?8.1 ± 7.7 µm (7/?23.2) between SD-OCT and NSM, and 1.8 ± 12.3 µm (25.9/?22.3) between USP and NSM.

Conclusions: USP and NSM were found to have comparable CCT measurements and these two methods can be used correspondingly. However, CCT measurements by SD-OCT were lower when compared to other methods.     

Evaluation of the Effect of Uncomplicated Cataract Surgery on Retina and Optic Disc: Optical Coherence Tomography Angiography Study

PurposeThe aim of the present study is to evaluate the effects of uncomplicated cataract surgery on microvascular structure of fovea, parafovea, optic disc, and peripapillary area with optical coherence tomography angiography (OCTA).MethodsThe study included 53 eyes of 53 patients, who undergone uncomplicated cataract surgery. The day before cataract surgery and at the 1st week, 1st month, 3rd month after surgery, best-corrected visual acuity, foveal avascular zone, acircularity index, superficial and deep foveal density, superficial and deep parafoveal density, central macular thickness, peripapillary retinal nerve fiber layer thickness value, and peripapillary vascular density were measured with OCTA.ResultsThe mean age of the patients was 62.1 ± 7.2 years (range, 42–69 years) and the sex of the patients was 25 male and 28 female. The foveal avascular zone value was decreased compared to the preoperative value (p < 0.05). There was no significant change in acircularity index postoperatively (p > 0.05). There was a significant increase in superficial and deep foveal density and superficial and deep parafoveal density (p < 0.05). According to preoperative period, peripapillary retinal nerve fiber layer and inside disc capillary density of optic disc increased significantly (p < 0.05). There was no significant change in peripapillary vascular density postoperatively (p > 0.05).ConclusionsChanges in the vascular density of the retina were detected with OCTA in eyes without ocular or systemic disease, which underwent uncomplicated cataract surgery. In the postsurgical period, OCTA provides important information in the evaluation and follow-up of these changes.     

Visualization of Sarcoid Choroidal Granuloma by Enhanced Depth Imaging Optical Coherence Tomography

Abstract

Purpose: To report, in vivo, on the quasi-histologic characteristics of a sarcoid choroidal granuloma as visualized by Enhanced Depth Imaging Spectral Domain Optical Coherence Tomography (EDI SD-OCT).

Methods: A 49 year-old woman showing a choroidal granuloma secondary to sarcoidosis was imaged by EDI OCT.

Result: On EDI SD-OCT examination, sarcoid choroidal granuloma appears as a localized hyporeflectivechoroidalthickening. Two weeks after systemic corticosteroids, the thickness of the granuloma decreased from 568?μm to 356?μm. Five months later, it reached 274?μm, and after eleven months, it decreased to 150?μm.

Conclusion: EDI SD-OCT allows direct visualization of choroidal granuloma secondary to sarcoidosis and evaluation of lesion regression after treatment.     

Application of Tear Meniscus Measurement by Anterior Segment Optical Coherence Tomography in the Diagnosis of Dry Eye

 Dry eye is one of the most frequent ocular surface diseases caused by complex ocular function and mechanism disorders. Currently, the standard diagnosis of dry eye has not been unified. Traditional clinical examinations provided inaccurate measurement and poor reproducibility due to various factors. Anterior segment optical coherence tomography (OCT) is applicable in the diagnosis of dry eye due to high resolution, non-invasiveness,good accuracy and  repeatability.     

Anterior Segment Optical Coherence Tomography: Assisted Topographic Corneal Epithelial Thickness Distribution Imaging of a Keratoconus Patient

Purpose

To evaluate safety, efficacy and ease of measurement of epithelial thickness in a keratoconic patient based on anterior segment optical coherence tomography (AS-OCT).

Methods

A 25-year-old male patient, previously diagnosed with keratoconus, with highly asymmetric manifestation among the two eyes, was subjected to AS-OCT corneal epithelial imaging. We investigated epithelial thickness and epithelial topographic thickness distribution.

Results

Mean epithelial thickness was 51.97 ± 0.70 for the less affected right eye (OD), and 55.65 ± 1.22 for the more affected left eye (OS). Topographic epithelial thickness variability for the OD was 1.53 ± 0.21 μm, while for the OS it was 9.80 ± 0.41 μm.

Conclusions

This case further supports our previous findings with high-frequency ultrasound measurements of the increase in overall epithelial thickness in keratoconic eyes in comparison with normal eyes. AS-OCT further offers ease of use and possibly higher predictability of measurement. This case report, based on AS-OCT imaging, verifies increased overall epithelial thickness in keratoconic eyes, as introduced by a previous study [Kanellopoulos et al.: Clin Ophthalmol 2012;6:789–800], based on high-frequency scanning ultrasound biomicroscopy imaging.Key words: Anterior segment optical coherence tomography, Keratoconus, Epithelial imaging, Pentacam HR     

Assessment of Scleral Contour Changes in High Myopia by Optical Coherence Tomography

PurposeThis study aimed to establish and validate optical coherence tomography (OCT) based diagnostic criteria of high myopia.MethodsThis was a cross-sectional study including 100 eyes of high myopia with axial length larger than 26.5 mm and 100 control eyes, which were examined by spectral-domain OCT. Vertical and horizontal OCT of 9 mm scanning across fovea were analyzed. OCT characteristics including mirror artifact, scleral sink due to steep inclination of posterior sclera, scleral visibility, abnormality of outer retinal layer, foveoschisis, and dome-shaped macula were assessed in each group.ResultsThe mean axial length was 28.65 ± 2.07 mm (range, 26.51–34.59 mm) in high myopia group and 23.79 ± 0.99 mm (range, 21.26–25.94 mm) in control group. Among the OCT characteristics noted at high frequency in the eyes with high myopia, three criteria achieving high sensitivity and specificity were determined: scleral sink over 500 μm, scleral visibility over 100 μm, and dome-shaped macula. Under conditions of presence of any of three criteria in either horizontal or vertical OCT scanning, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value for high myopia were found to be 95.0%, 98.0%, 98.0%, and 95.1%, respectively. In a new set of OCT images from 50 eyes with high myopia and 50 eyes of nonhigh myopia cases, the OCT-based criteria also proved similar level of diagnostic validity.ConclusionsThe OCT-based criteria, which directly addressed posterior scleral contour changes, may lead to an intuitive and accurate diagnosis of high myopia. Also, the criteria may contribute to early detection and monitoring of eyes that cannot be defined as high myopia but can progress. OCT may be useful for monitoring high myopia patients as OCT can detect myopia-associated retinal pathologies as well as scleral contour changes.     

光学相干断层成像在中心性浆液性脉络膜视网膜病变激光治疗中应用

目的 探讨光学相干断层成像(OCT)在中心性浆液性脉络视网膜病变(CSC)诊断、疗效观察及随访中的应用价值.方法 对112例116只眼经检查确诊的中心性浆液性脉络膜视网膜病变患者激光前后进行OCT和荧光素眼底血管造影(FFA)检查,采用OCT对CSC激光治疗前、后不同时期视网膜神经上皮脱离范围和高度进行定量分析.结果 116只眼OCT图像均表现为单纯视网膜神经上皮层脱离.将116只眼分别于激光前、激光后1周、2周视网膜神经上皮脱离范围、高度进行比较,经T检验,差异有统计学意义.激光后4周,OCT检查视网膜神经上皮层脱离恢复正常83只眼(占71.55%),激光后6周OCT检查正常111只眼 (占95.69%),1次激光封闭112只眼 (占96.55%),2次激光封闭4只眼(占3.45%).116眼全部治愈.结论 OCT在CSC诊断、疗效观察、病程随访中能客观定量地反映黄斑部视网膜的各层细微结构的动态变化,并进行综合分析,有较高的临床实用价值.     

Microvasculature Recovery Detected Using Optical Coherence Tomography Angiography and the Rate of Visual Field Progression After Glaucoma Surgery

PurposeWe evaluated microvascular changes using optical coherence tomography angiography (OCT-A) in glaucoma patients who underwent glaucoma surgery.MethodsThe macula and optic nerve head were imaged using an OCT-A device at one day before surgery and at one week, one month, three months, and six months after surgery. Measurements of vessel density (VD) were made in the intradisc region and macula, and the area of the foveal avascular zone (FAZ) was measured in both superficial and deep vascular layers. A mean deviation (MD) slope value of < −1.0 decibel/y was considered to be indicative of VF progression.ResultsA significant increase in VD was observed postoperatively in the deep vascular layer of the intradisc area (P < 0.001), and a significant decrease in the FAZ area was evident in the deep vascular layer (P = 0.018). An increase in the intradisc deep VD (17.48% ± 5.63%) was statistically significant in glaucoma eyes without progression, compared with those with progression (−1.27% ± 2.19%). Worse preoperative MD of the VF (P = 0.006), lower preoperative intradisc VD (P < 0.001), and fewer changes in the intradisc deep VD after surgery (P < 0.001) were significantly associated with MD slope.ConclusionsWe found deep VD changes in the laminar region of the optic nerve head and the macular area at up to postoperative one month after glaucoma surgery. An increase in the deep VD in the laminar region was beneficial to VF progression in glaucoma patients after surgery.     

iOCT在病理性近视黄斑病变手术中的应用

目的：在病理性近视黄斑病变的手术治疗中评估术中光学相干断层扫描(iOCT)的可行性,并探讨其术中应用价值。方法：回顾性系列病例研究。收集2015年5月至2017年12月期间于温州医科大学附属眼视光医院杭州院区行玻璃体切除术的黄斑前膜、黄斑裂孔、黄斑劈裂及玻璃体黄斑牵拉综合征等病理性近视黄斑病变患者。所有患眼术中均行iOCT检查,定性评估术中视网膜变化,包括术中微损伤、手术技术准确性及裂孔边缘改变等,探讨其术中应用的价值。结果：本研究共纳入29例（29眼）,男9例,女20例;年龄（58.8±10.3）岁;眼轴长度（28.9±2.0）mm。其中,黄斑前膜14眼,黄斑裂孔8眼,黄斑劈裂4眼及玻璃体黄斑牵拉综合征3眼。iOCT显示：7眼（7/29）确认术中存在微损伤或异常情况,其中神经纤维层异常6眼,内层视网膜抬高1眼;黄斑前膜患眼中4眼（4/14）确认剥膜后前膜残留;黄斑裂孔患眼中3眼（3/8）剥膜后观察到孔缘形态改变;黄斑劈裂患眼中均未观察到剥膜后全层黄斑裂孔的发生,其中1眼术前未明确的黄斑裂孔经iOCT确认;术中行保留中心凹内界膜或内界膜翻转覆盖术式的3眼在iOCT图像中均得到确认。结论：iOCT有助于术中实时评估剥膜的完整性、术中微损伤情况及手术技术的精确性,帮助主刀医师提高黄斑裂孔的诊出率,并可在术中观察到黄斑裂孔剥膜后孔缘形态的特殊改变,提示iOCT在病理性近视黄斑病变的手术治疗中有一定的应用价值。     

Assessment for Macular Thickness after Uncomplicated Phacoemulsification Using Optical Coherence Tomography

PurposeMacular edema including cystoid macular edema is one of the main causes of unfavorable visual outcomes after cataract surgery. The macular thickness and the occurrence of macular edema after uncomplicated cataract surgery was evaluated using optical coherence tomography (OCT) in this study.MethodsMacular map images were taken by OCT before surgery and at 1 week, 1 month, and 2 months postsurgery. The subjects were classified into two groups (group 1, patients with no macular edema; group 2, patients with macular edema). Group 2 was defined as increase in central macular thickness (CMT) by 30% compared with that before surgery. The risk factors for macular edema were evaluated. Group 2 was divided into two subgroups: subclinical macular edema (group 2A) and cystoid macular edema (group 2B) and they were assessed in terms of the clinical course of best-corrected visual acuity and CMT.ResultsA total of 376 patients were enrolled in this study, of which 36 (9.57%, group 2) showed macular edema measured by OCT after the surgery. Univariate analysis for group 1 and 2 revealed that intracameral injection of epinephrine during phacoemulsification was associated with the development of macular edema. In group 2, five patients (1.33%) developed cystoid macular edema. Statistically significant differences in the clinical course of CMT were observed at 2 months (201.2 ± 23.1, 250.0 ± 29.8, and 371.0 ± 160.3 in group 1, group 2A, and group 2B, respectively; p < 0.001) and 1 month postoperatively (198.5 ± 23.6, 237.8 ± 40.9, and 314.0 ± 104.5 in group 1, group 2A, and group 2B, respectively; p < 0.001). Group 2B required additional treatment and eventually achieved best-corrected visual acuity of >0.2 with CMT in the normal range.ConclusionsThe intracameral injection of epinephrine may cause macular edema after uncomplicated cataract surgery. Examination of CMT using OCT is recommended for the early detection of macular edema.     

The Top 100 Papers of 25 Years of Macular Imaging Using Optical Coherence Tomography

We analyzed and quantified the 100 most frequently cited papers in macular imaging using optical coherence tomography (OCT). The databases of the Institute for Scientific Information databases utilized for identification of articles in macular imaging using OCT over the last 25 years since the introduction of OCT in ophthalmology. All articles containing “optical coherence tomography” and “retina” without “glaucoma”. The publication dates of the 100 most-cited articles ranged from 1991 to 2015, with the greatest number of articles published in the 2000s, while the total number of citations per article was greatest for articles published in the 1990s. Most studies were conducted in the U.S. and represented Level-IV clinical outcome studies indicating that also small case series or cohort studies could gain attention. The top 5 senior authors contributed to 39 of the 100 selected publications and accrued a total of 66.0% of all citations of those articles.     

视网膜静脉阻塞中心凹周围视网膜厚度的OCT观察

目的：分析视网膜静脉阻塞患者中心凹两侧视网膜的光学相干断层成像(OCT)特征。方法：40例视网膜静脉阻塞患者(40眼)行OCT检查。其中CRVO30例，BRVO10例。结果：CRVO中心凹鼻侧视网膜厚度大于颞侧，BRVO中心凹阻塞侧视网膜厚度大于对侧。阻塞远端的视网膜结构变化较小，阻塞近端的视网膜结构变化较大。结论：OCT可以有效地观察视网膜静脉阻塞患者后极部中心凹两侧视网膜的变化，静脉阻塞近端的视网膜结构损害比远端更加严重。