Ultra high-resolution anterior segment optical coherence tomography in the diagnosis and management of ocular surface squamous neoplasia

The development of optical coherence tomography (OCT) technology has helped to usher in a new era of in vivo diagnostic imaging of the eye. The utilization of OCT for imaging of the anterior segment and ocular surface has evolved from time-domain devices to spectral-domain devices with greater penetrance and resolution, providing novel images of anterior segment pathology to assist in diagnosis and management of disease. Ocular surface squamous neoplasia (OSSN) is one such pathology that has proven demonstrable by certain anterior segment OCT machines, specifically the newer devices capable of performing ultra high-resolution OCT (UHR-OCT). Distinctive features of OSSN on high resolution OCT allow for diagnosis and differentiation from other ocular surface pathologies. Subtle findings on these images help to characterize the OSSN lesions beyond what is apparent with the clinical examination, providing guidance for clinical management. The purpose of this review is to examine the published literature on the utilization of UHR-OCT for the diagnosis and management of OSSN, as well as to report novel uses of this technology and potential directions for its future development.

Macular choroidal thickness profile in a healthy population measured by swept-source optical coherence tomography

PURPOSE

To determine choroidal thickness (CT) profile in a healthy population using swept-source optical coherence tomography (SS-OCT).

METHODS

This was a cross-sectional, noninterventional study. A total of 276 eyes (spherical equivalent ± 3 diopters [D]) were scanned with SS-OCT. Horizontal CT profile of the macula was created measuring subfoveal choroidal thickness (SFCT) from the posterior edge of retinal pigment epithelium (RPE) to the choroid-sclera junction. Three determinations were performed at successive points 1000 μm nasal and five more temporal to the fovea. Subjects were divided into five age groups.

RESULTS

The mean SFCT was 301.89 ± 80.53 μm (95% confidence interval: 292.34-311.43). The mean horizontal macular choroidal thickness (MCT) was 258.69 ± 64.59 μm (95% confidence interval: 251.04-266.35). No difference in CT was found between men and women. Mean SFCT of the different study groups was 325.6 ± 51.1 (0-10 years), 316.7 ± 90.1 (11-20 years), 313.9 ± 80.3 (21-40 years), 264.6 ± 79.3 (41-60 years), and 276.3 ± 88.8 μm in subjects older than 60 years (P < 0.001; ANOVA test). Mean horizontal MCT was 286.0 ± 43.5, 277.7 ± 68.2, 264.0 ± 61.9, 223.4 ± 62.2, and 229.7 ± 66.1 μm, respectively (P < 0.001; ANOVA test). The CT profile was different for each age group.

CONCLUSIONS

To our knowledge, this is the first population study of CT of healthy eyes across a broad range of age groups using SS-OCT. As has been determined using spectral-domain OCT, CT decreases with advancing age, especially after age 40. There were no differences due to sex. The greatest CT variation takes place in temporal sectors.

Macular OCT Characteristics at 36 Weeks' Postmenstrual Age in Infants Examined for Retinopathy of Prematurity

PURPOSE

To report our ability to capture,-grade reliably, and analyze bedside macular OCT images from preterm infants and relate OCT findings to biological factors and retinopathy of prematurity (ROP) status at a single time window in the Study of Eye Imaging in Preterm Infants (BabySTEPS).

DESIGN

Prospective, observational study.

PARTICIPANTS

Preterm infants eligible for ROP screening with parental consent for research and a 36 ± 1 weeks' postmenstrual age (PMA) visit.

METHODS

We imaged both eyes of preterm infants with an investigational noncontact, handheld swept-source (SS) OCT at the time of clinical ROP examinations. Macular OCT features and layer thicknesses for untreated eyes of infants at 36 ± 1 weeks' PMA were compared with demographic data and clinical ROP examination performed by experts. Statistical analyses accounted for the use of both eyes of infants.

MAIN OUTCOME MEASURES

Macular OCT features and layer thicknesses, gender, race or ethnicity, gestational age, birth weight, ROP stage, and plus disease.

RESULTS

We captured macular OCT from 169 eyes (1 eye excluded because of prior ROP treatment) at 36 ± 1 weeks' PMA. The quality of OCT volumes was excellent in 33 eyes (19%), acceptable in 112 eyes (67%), poor in 24 eyes (14%), and unusable in 0 eyes (0%). Macular edema was present in 60% of eyes and was bilateral in 82% of infants with edema. At the fovea, retinal and inner nuclear layer thickness increased with edema severity: 183 ± 36 μm and 51 ± 27 μm in mild (16% of eyes), 308 ± 57 μm and 163 ± 53 μm in moderate (25%), and 460 ± 76 μm and 280 ± 83 μm in severe edema (12%), respectively. With an increase in ROP stage from 0 to 2, the mean ± standard deviation retinal thickness at the fovea increased from 227± 124 μm to 297 ± 99 μm (P < 0.001). The choroid was thinner, 155 ± 72 μm, with preplus or plus disease versus without, 236 ± 79 μm (P = 0.04), whereas retinal thickness did not vary.

CONCLUSIONS

We demonstrated the reliability of methods and the prevalence of OCT findings in preterm infants enrolled in BabySTEPS at a single time point of 36 ± 1 weeks' PMA. Variations in layer thicknesses in infants at this time point may reflect abnormalities resulting from delay in foveal development that may be impacted by macular edema, ROP, or both.

Macular Choroidal Thickening in Keratoconus Patients: Swept-Source Optical Coherence Tomography Study

Purpose

To determine the choroidal thickness (CT) profile in keratoconus (KC) patients using swept-source optical coherence tomography (SS-OCT).

Methods

This was a prospective, cross-sectional study. One hundred two eyes of 52 KC patients were studied using Pentacam and SS-OCT. The macular CT profile was created by manually measuring the distance between the retinal pigment epithelium and the choroid-sclera junction on horizontal b-scans at nine different macular locations. The results were compared to 93 eyes of 93 healthy controls.

Results

Mean age of the KC group was 34.9 ± 13.5 years and mean axial length (AL) was 24.1 ± 1.3 mm. Mean topographic KC classification (TKC) was 2.0; 39 eyes were classified as early KC (TKC <1–2), 34 eyes as moderate (TKC 2, 2–3), and 29 as advanced (TKC 3+). Mean subfoveal CT was 383.2 μm in KC patients and 280.5 μm in control group (P < 0.001). CT in KC patients was statistically thicker in all measure locations (P < 0.001). CT in KC eyes decreased with age, approaching control group at >45 years old, losing statistical significance (P = 0.37).

Conclusions

CT in KC patients is statistically thicker than in healthy population. After age 45, CT decreases approaching control group values.

Translational Relevance

This study describes changes in the CT profile of KC patients, a disease that was considered purely corneal. These choroidal changes argue that KC is a disease that likely involves several ocular structures other than the cornea, and could open new research lines related to the pathophysiology of KC.

Importance of Paravascular Vitreal Adhesions for Development of Myopic Macular Retinoschisis Detected by Ultra-Widefield OCT

PURPOSE

To examine most postequatorial retina in eyes with myopic macular retinoschisis (MRS) by ultra-widefield (UWF) OCT and to determine whether paravascular vitreal adhesions play a role in the development of MRS.

DESIGN

Retrospective single-center observational case series.

PARTICIPANTS

One hundred fifty highly myopic participants who were older than 50 years with and without an MRS were studied. High myopia was defined as an eye with an axial length of more than 26.5 mm.

METHODS

All participants underwent UWF OCT imaging with a scan width of 23 mm and a depth of 5 mm using a prototype swept-source OCT device. The vitreoretinal adhesions to the foveal retina and retinal vessels and paravascular abnormalities, including paravascular retinal cysts, paravascular retinoschisis, and paravascular lamellar holes, were analyzed in the UWF OCT images. The findings in eyes with an MRS were compared with those in eyes without an MRS.

MAIN OUTCOME MEASURES

The relationships between MRS and vitreal adhesions to the retinal vessels or to the fovea were determined.

RESULTS

An MRS was found in 49 of the 150 eyes (33%). Vitreal adhesions to the retinal vessels were found more frequently in eyes with an MRS than in eyes without an MRS (63% vs. 44%; P = 0.04). In contrast, the number of eyes with adhesions to the fovea in eyes with an MRS was not significantly different from that in eyes without an MRS (57% vs. 59%). Paravascular lesions, for example, retinal cysts, retinoschisis, and lamellar holes, were more common in eyes with an MRS than in eyes without an MRS (71% vs. 36%, 61% vs. 17 %, and 20% vs. 8% [P < 0.001, P < 0.001, and P = 0.03], respectively). Multivariate analysis showed that the presence of paravascular vitreal adhesions was a significant predictor for MRS development (odds ratio, 2.56; P = 0.02).

CONCLUSIONS

Paravascular vitreal adhesions may be related to the development of the different types of paravascular lesions including retinal cysts and retinoschisis, and play a more important role in the development of an MRS than vitreal adhesions to the fovea.

Characterization of macular choroid in normal-tension glaucoma: a swept-source optical coherence tomography study

PURPOSE

To investigate the features of the small-to-medium (choriocapillaris and Sattler's layer) and large (Haller's layer) sized vessel layers of the macular choroid in normal-tension glaucoma (NTG) patients using swept-source optical coherence tomography (SS-OCT).

METHODS

We conducted an observational cross-sectional study in 234 NTG eyes from 134 patients, and 203 normal eyes from 109 non-glaucomatous control subjects. We used Image J to segment the choroidal layer and then a Python script to measure the average macular choroidal thickness (MCT) and choroidal vascular index (CVI) of two vessel layers at five different locations. Quantitative optical coherence tomography angiography (OCTA) metrics for the superficial capillary plexus (SCP) and deep capillary plexus (DCP) at macular region were also measured by a customized MATLAB program. Generalized estimating equations (GEE) models were performed to determine ocular and demographic factors associated with the choroidal metrics, adjusting for inter-eye correlation.

RESULTS

Significant average MCT thinning was found in NTG eyes at all five locations of the two layers, in comparison with controls (all p ≤ 0.05). In addition, compared with control eyes, significant decrease in CVI was found in NTG eyes at all five sections of the large sized vessel layer: 500 µm nasal and temporal to macula (p = 0.002), 1500 µm nasal (p < 0.001), 2500 µm nasal (p = 0.001), 1500 µm temporal (p < 0.001) and 2500 µm temporal (p = 0.004). In contrast, no significant CVI difference was detected in the small-to-medium sized vessel layer. In the comparison of OCTA metrics of SCP and DCP at macular region between NTG and normal eyes, there were no significant difference of parafoveal vessel density (VD), foveal avascular zone (FAZ) area, FAZ circularity and fractal dimension (FD) in both layers.

CONCLUSION

We found significant alterations in macular choroidal vascularity (reduced CVI and thinner layer) in NTG patients. Such alterations are more pronounced in the Haller's layer, rather than the choriocapillaris & Sattler's layer, in NTG. Choroidal layer may be more related to vasculature changes at macular region in NTG.

Volumetric parameters-based differentiation of narrow angle from open angle and classification of angle configurations: an SS-OCT study

BACKGROUND

To evaluate the diagnostic ability of volumetric parameters to differentiate narrow angle from open angle and distinguish different configurations of narrow angle.

METHODS

The current study was composed of two parts. In the first part, with gonioscopy as reference standard, we tested power of each parameter to differentiate narrow angle from open angle. In the second part, we evaluated the efficacy of different parameters to distinguish angle configurations which were subclassified into type 1 (pupillary block) and type 2 (non-pupillary block and multiple mechanisms) based on ultrasound biomicroscopy (UBM) images.

RESULTS

In part 1, the training set was composed of 117 narrow-angle eyes and 60 open-angle eyes, and the validation set included 38 narrow-angle eyes and 37 open-angle eyes. Anterior chamber volume (ACV) outperformed all the other parameters with an area under the curve (AUC) of 0.988. The sensitivity and specificity of the cut-off value 98.1 mm³ in the validation set were 90.0% and 97.1%, respectively. In part 2, training set was composed of 96 eyes of 88 patients with primary angle-closure disease, with 49 diagnosed as type 1 and 47 as type 2 configuration. 32 eyes were used for validation. A model comprised of iris volume (IV), iris thickness (IT) 2000 µm from the scleral spur and angle open distance (AOD) 750 µm from the scleral spur was found to have an AUC of 0.793 (95% CI, 0.695 to 0.870). Sensitivity and specificity of the model were 82.6% and 77.8% respectively in the validation set.

CONCLUSIONS

With ACV, we can detect patients with narrow angle from open angle faster and more easily than AOD and anterior chamber depth. Then, for patients with narrow angle, the combination of IV, IT and AOD750 measured by swept-source optical coherence tomography could further classify configurations of angle closure compared with UBM.

Characterization of Choroidal Morphology and Vasculature in the Phenotype of Pachychoroid Diseases by Swept-Source OCT and OCTA

The objective of this study was to characterize the choroidal morphology and vasculature in pachychoroid diseases (PCD). A total of 49 eyes with polypoidal choroidal vasculopathy (PCV), 43 eyes with neovascular age-related macular degeneration (nAMD), and 50 eyes with central serous chorioretinopathy (CSC), along with 80 healthy eyes, were enrolled in this nested case-control study. The swept-source optical coherent tomography (OCT), OCT angiography, and En face images were quantitatively analyzed. Multivariate logistic regression models showed that older age and increased vessel density (VD) in the choriocapillaris (CC) layer were independent risk factors for both PCV (page < 0.001, pVD = 0.004), and nAMD (page < 0.001, pVD = 0.005). Decreased VD in the Sattler’s layer was an independent risk factor for PCV (p = 0.014). Increased VD in the Haller’s layer was an independent risk factor for CSC (p = 0.001). The proportion of the diffuse type of collateral circulation in the Sattler’ layer in CSC group was significantly higher than in the other three groups (p < 0.001). We concluded that the involvement of the blood flow in the CC, Haller’s, and Sattler’s layers are differently affected in CSC, nAMD, and PCV eyes, indicating the different pathological mechanism underlying the phenotype of PCD. The age-dependent establishment of collateral circulation in the Sattler’s layer may play a compensatory role regarding ischemic injury in the development of PCD.

Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

The non-destructive classification of plant materials using optical inspection techniques has been gaining much recent attention in the field of agriculture research. Among them, a near-infrared (NIR) imaging method called optical coherence tomography (OCT) has become a well-known agricultural inspection tool since the last decade. Here we investigated the non-destructive identification capability of OCT to classify diversely stained (with various staining agents) Capsicum annuum seed specimens of different cultivars. A swept source (SS-OCT) system with a spectral band of 1310 nm was used to image unstained control C. annuum seeds along with diversely stained Capsicum seeds, belonging to different cultivar varieties, such as C. annuum cv. PR Ppareum, C. annuum cv. PR Yeol, and C. annuum cv. Asia Jeombo. The obtained cross-sectional images were further analyzed for the changes in the intensity of back-scattered light (resulting due to dye pigment material and internal morphological variations) using a depth scan profiling technique to identify the difference among each seed category. The graphically acquired depth scan profiling results revealed that the control specimens exhibit less back-scattered light intensity in depth scan profiles when compared to the stained seed specimens. Furthermore, a significant back-scattered light intensity difference among each different cultivar group can be identified as well. Thus, the potential capability of OCT based depth scan profiling technique for non-destructive classification of diversely stained C. annum seed specimens of different cultivars can be sufficiently confirmed through the proposed scheme. Hence, when compared to conventional seed sorting techniques, OCT can offer multipurpose advantages by performing sorting of seeds in respective to the dye staining and provides internal structural images non-destructively.

Imaging choroidal neovascular membrane using en face swept-source optical coherence tomography angiography

Purpose

The aim of this study was to assess the efficacy of swept-source optical coherence tomography angiography (SS-OCTA) in delineating the morphology of choroidal neovascular membrane (CNV).

Patients and methods

This was a retrospective observational case series reviewing clinical data and fundus fluorescein angiography (FFA), swept-source optical coherence tomography (SS-OCT), and SS-OCTA images of patients with CNV and comparing the findings. The swept-source technology enables deeper penetration and superior axial resolution. The incorporated blood flow detection algorithm, optical coherence tomography angiography ratio analysis (OCTARA), enables visualization of CNV in vivo without the need for dye injection.

Results

The study included 136 eyes of 105 patients. Active lesions on SS-OCTA images showed increased capillary density, extensive arborization, vascular anastomosis and looping, and peri-lesional hollow. Inactive lesions showed decreased capillary density, presence of large linear vessels, and presence of feeder vessels supplying the CNV. We detected positive correlation between SS-OCTA, FFA, and SS-OCT images in 97% of eyes. In the remaining 3%, SS-OCTA confirmed the absence of CNV, whereas FFA and SS-OCT either were inconclusive in the diagnosis of CNV or yielded false-positive results.

Conclusion

SS-OCT and SS-OCTA represent a reproducible risk-free analog for FFA in imaging CNV. SS-OCTA is particularly versatile in cases where FFA and SS-OCT are inconclusive.

Thin minimal rim width at Bruch's membrane opening is associated with glaucomatous paracentral visual field loss

Purpose

To compare optic nerve head (ONH) measurements in glaucomatous eyes with paracentral visual field (VF) loss to eyes with peripheral VF loss and controls.

Methods

Open-angle glaucoma (OAG) patients with early paracentral VF loss or isolated peripheral VF loss as well as control subjects underwent ONH imaging with swept-source optical coherence tomography (OCT) and retinal nerve fiber layer (RNFL) imaging with spectral-domain OCT. Minimum rim width at Bruch's membrane opening (BMO-MRW), lamina cribrosa depth (LCD), and RNFL thickness were compared among the glaucoma and control groups with one-way analysis of variance, Kruskal-Wallis test, and multiple regression analysis.

Results

Twenty-nine eyes from 29 OAG patients (15 early paracentral and 14 isolated peripheral VF loss) and 20 eyes of 20 control subjects were included. The early paracentral and isolated peripheral VF loss groups had similar VF mean deviation (MD) (-5.3±2.7 dB and -3.7±3.0 dB, p=0.15, respectively). Global BMO-MRW was lower in OAG eyes than in controls (193.8±40.0 vs 322.7±62.2 μm, p<0.001), but similar between eyes with early paracentral VF loss and those with isolated peripheral VF loss (187.6±43.4 vs 200.6±36.3 μm; p>0.99). In contrast, the minimal BMO-MRW was lower in eyes with early paracentral loss (69.0±33.6 μm) than in eyes with isolated peripheral loss (107.7±40.2 μm; p=0.03) or control eyes (200.1±40.8 μm; p<0.001). Average and thinnest RNFL thickness did not differ between OAG groups (p=0.61 and 0.19, respectively). Horizontal and vertical LCD did not differ among the OAG groups and controls (p=0.80 and 0.82, respectively). Multivariable linear regression analysis among OAG cases confirmed the association between lower minimal BMO-MRW and early paracentral VF loss (β=-38.3 μm; 95% confidence interval, -69.8 to -6.8 μm; p=0.02) after adjusting for age, gender, MD, and disc size.

Conclusion

Thin minimal BMO-MRW may represent a new structural biomarker associated with early glaucomatous paracentral VF loss.

Ocular biometry in dense cataracts: Comparison of partial-coherence interferometry, swept-source optical coherence tomography and immersion ultrasound

Purpose:

To assess the axial length (AL) measurement failure rate using partial-coherence interferometry (PCI) and swept-source optical coherence tomography (SS-OCT) in dense cataracts. As a secondary outcome, the SS-OCT biometry was compared to immersion ultrasound.

Methods:

This is a prospective cross-sectional and comparative study. Seventy eyes from 70 patients with dense cataracts were enrolled in this study. Dense cataract was defined according to the Lens Opacities Classification System III (LOCS III) scores equal to or more than NO4, NC4, C4, and P3. The failure rate of AL measurement was evaluated using PCI and SS-OCT. Anterior chamber depth (ACD), lens thickness (LT), and AL measurements obtained by SS-OCT were compared with IUS.

Results:

AL measurement failure rate with PCI was 68.57% and 21.43% with SS-OCT (P = 0.007). AL measurement was achieved in 69.23% of NO4, 66.6% of P3, and 15.3% of mixed cataracts using PCI, while SS-OCT was achieved in 100% of NO4, NO5, P3, and P5 and 76.9% of mixed cataracts. Cortical cataracts alone did not influence AL measurement. Biometric data of ACD, LT, and AL were statistically different comparing US and SS-OCT with a good correlation of AL.

Conclusion:

SS-OCT significantly improves the rate of successful AL measurements when compared to PCI in dense cataracts. The LOCS III clinical cut-off for the use of SS-OCT ocular biometry may well be up to P4 and NO5.

Effect of Pterygium Removal Combined with Conjunctival Autograft on Corneal Parameters in Swept-Source Imaging

Background: Both pterygium ingrowth and excision determine alterations in corneal topography. The aim of this study was to evaluate the influence of pterygium removal combined with conjunctival autografts in addition to the use of human fibrin tissue glue on changes in corneal parameters as measured by 3-D swept-source anterior segment optical coherence tomography (AS-OCT) imaging. Methods: Sixteen eyes (16 patients) with pterygium that qualified for surgical treatment were enrolled in this study. Eye examination, slit lamp, and 3-D AS-OCT (CASIA 2) assessment were performed before the surgery and 7 days, 1 month, and 6 months after pterygium excision. Topographic parameters of both anterior and posterior surfaces of the cornea were analysed at each follow-up visit. Results: The gradual decrease in total astigmatism power from preoperative median 2.75 (6.15) D to 1.2 (1.1) D at 6-month follow-up (p = 0.034) was noted from the day 7 visit. Values were strongly influenced by variations of anterior cornea astigmatism. In contrast, a gradual total HOA reduction at the 1-month (from median 0.79 (1.3) D to 0.44 (0.27) D; p = 0.038) and at 6-month visits (0.25 (0.09); p = 0.001) was observed. Similarly, values were strongly influenced by variations of the anterior. Additionally, total average keratometry values increased from preoperative 44.05 (2.25) D to 44.6 (1.9) (p = 0.043) 1 month after the surgery. Conclusions: Significant steepening of the anterior cornea and a reduction in both astigmatism and HOA were observed after pterygium excision. The anterior corneal surface was an essential component of the total postoperative corneal topography values. Three-dimensional swept-source AS-OCT imaging seems to be a valuable tool for monitoring both the progression of the disease and postoperative effects in pterygium eyes.

Biometric Differences between Unilateral Chronic Primary Angle Closure Glaucoma and Fellow Non-Glaucomatous Eyes

PURPOSE

To compare biometric differences between eyes with unilateral chronic primary angle-closure glaucoma (PACG) and fellow non-glaucomatous eyes in the same patient.

METHODS

Clinical data and imaging records of 17 patients with unilateral PACG were retrospectively reviewed. The fellow eyes with primary angle-closure (PAC) or primary angle-closure suspected (PACS) were grouped in Group 1. The PACG eyes were set as Group 2. The biometric parameters of both eyes were measured by IOL-Master, anterior segment optical coherence tomography (AS-OCT), and swept source OCT.

RESULTS

The iris area in Group 1 was significantly thicker than that in Group 2 (1.590 ± 0.267 versus 1.365 ± 0.352, P = 0.016). Choroidal thickness in the macular region was thicker in Group 1 than in Group 2, with statistical significance at inner temporal grid (282.7 ± 121.1 versus 191.6 ± 90.3, P = 0.036), central field (297.4 ± 130.6 versus 200.1 ± 96.3, P = 0.029), inner nasal grid (283.1 ± 128.3 versus 194.8 ± 91.8, P = 0.040), and average value (265.3 ± 105.6 versus 191.1 ± 87.0, P = 0.049). Group 1 also had thicker peripapillary choroidal thickness at 1 o'clock (141.4 ± 68.4 versus 101.8 ± 39.0, P = 0.025) and 12 o'clock (141.5 ± 82.3 versus 104.5 ± 44.6, P = 0.037) compared to Group 2. The multivariate logistic regression analyses showed that only intraocular pressure was independently associated with PACG and explained 58.3% variance of PACG.

CONCLUSIONS

In unilateral PACG, there was significant inter-eye difference in anterior and posterior segment parameters. Longitudinal comparisons are required to further understand the differences in pathology of angle closures.

Sequential imaging of a case of choroidal osteoma using swept-source OCT and optical coherence tomography angiography: A 4-year follow-up study

A 33-year-old gentleman was presented with metamorphopsia in the left eye due to choroidal osteoma (CO) complicated by choroidal neovascular membrane (CNVM). Optical coherence tomography angiography (OCTA) proved to be a valuable, noninvasive tool in monitoring treatment response of CNVM. The tumor subsequently underwent decalcification over a period of 4 years. In addition, SS-OCT scans were instrumental in documenting the natural course of the tumor and focal choroidal excavations (FCE), which were found in correspondence with tumor decalcification. Close follow-up is warranted in FCE, secondary to decalcification of CO, as CNVM has been documented to occur on the slope or bottom of eyes with FCE.

Horizontal Extraocular Muscle Insertion Site in Relation to Axial Length Using Swept-Source Anterior Segment OCT

Purpose

The purpose of this study was to correlate between the axial length of the globe and the insertion site of horizontal extraocular muscles using swept-source anterior segment optical coherence tomography (SS-ASOCT), with posing an equation to calculate the muscle insertion site from the axial length.

Methods

The study design was observational and cross-sectional. It was performed on 157 eyes of 157 healthy subjects. The distance of the medial rectus (MR) and the lateral rectus (LR) insertion sites from the limbus were measured using SS-ASOCT. The insertion sites’ distances were correlated to the axial length (hypermetropes < 22.5 mm, myopes > 24.5). Correlation between numerical variables was done by Pearson’s correlation coefficient and confirmed by linear regression analysis and scatter diagrams.

Results

The mean MR insertion site was 5.47 ± 0.19 mm in hypermetropes versus 5.68 ± 0.23 mm in myopes, whereas the mean LR insertion site was 6.81± 0.23 mm in hyperopes versus 7.08 ± 0.16 mm in myopes. The axial length showed a moderate positive, but significant, correlation to the insertional position for the medial and lateral rectus muscles (MR: r=0.417, p<0.001; LR: r=0.410, p<0.001).

Conclusion

Comparing the horizontal extraocular muscle insertion site to axial length using SS-ASOCT showed a significant positive correlation. The model equation for MR insertion: MR (mm) = 4.522 + 0.045 (AXL in mm) with an R = 0.437, R²= 0.191, F=12.071, P<0.001. The model equation for LR insertion: LR (mm) = 5.72 + 0.048 (AXL in mm) with an R = 0.438, R²= 0.192, F=12.116, P<0.001.

Photopsia and a temporal visual field defect

A 30-year-old woman presented with intermittent photopsia, a temporal visual field defect below the horizontal in her left eye, and flu-like symptoms. Slit-lamp and fundus examinations were unremarkable. Humphrey 30-2 threshold perimetry and 120-point screening visual field demonstrated blind spot enlargement of the left eye and a normal field in the right eye. Fundus autofluorescence, optical coherence tomography of the macula, full-field electroretinogram, electrooculogram, and multifocal electroretinogram were normal. Swept-source optical coherence tomography scan of the left optic nerve showed an intact outer retina, a remarkably thinned nerve fiber layer nasally, and peripapillary vitreous traction. Goldmann kinetic perimetry revealed a sector-shaped dense defect breaking out from the blind spot to the temporal periphery just below the horizontal in the left eye. The patient had nasal hypoplasia of the optic nerve and peripapillary vitreous traction.

Differences in swept-source OCT angiography of the macular capillary network in high tension and normal tension glaucoma

AIM OF THE STUDY

The purpose of the present study was to determine if swept-source optical coherence tomography angiography (OCTA) of the superficial plexus in the macular region can detect differences between high-tension open-angle glaucoma (HTG) and normal-tension glaucoma (NTG).

MATERIALS AND METHODS

In this prospective study 60 eyes from 60 patients (40 HTG; 20 NTG) underwent fovea centred 3 × 3 mm cube macula OCTA imaging by a swept-source OCTA device (Plex Elite, Zeiss, Jena, Germany). Quantitative analysis of the vasculature at the superficial plexus was performed by assessing the Perfusion Density (PD), defined as the total area of perfused vasculature per unit area in a region of measurement, for each group, respectively. Besides, macular ganglion cell layer thickness and mean deviation from visual field testing was assessed and correlated with PD.

RESULTS

Average superficial PD of the measured 3 × 3 mm field was comparable between HTG and NTG (P = .567). In both groups a significant relation of PD and age (HTG: r = -0.48, p = .002; NTG: r = -0.615; p = .004) was shown, indicating reduced PD with increasing age. For both groups a positive correlation between PD and mean deviation (MD) (HTG: r = 0.492, p = .003; NTG: r = 0.530, p = .029) as well as PD and GCL thickness was shown (r = 0.486, p = .002 vs. r = 0.389; p = .09). However, the latter did not reach statistical significance in the NTG group.

CONCLUSION

PD at the central 3 mm around the fovea is comparable between HTG and NTG. Significant correlation with age and MD was shown in both groups.

Infracyanine Green vs. Brilliant Blue G in Inverted Flap Surgery for Large Macular Holes: A Long-Term Swept-Source OCT Analysis

Background and Objectives: To compare the long-term toxicity of infracyanine green (IFCG) to brilliant blue G (BBG) in inverted internal limiting membrane flap surgery (I-ILMFS) for large, full-thickness macular holes (FTMHs). Materials and Methods: Prospective randomized study including 39 eyes with ≥ 400 µm idiopathic FTMH who underwent I-ILMFS with either IFCG or BBG. Postoperative 6- and 12-month corrected distance visual acuity (CDVA), closure rate, and swept-source optical coherence tomography parameters, including ellipsoid zone (EZ) and external limiting membrane (ELM) mean defect length, central foveal thicknesses (CFT), parafoveal macular thickness (MT), ganglion cells and inner plexiform layer (GCL++) thickness, and peripapillary nerve fiber layer (pRNFL) thickness, were compared. Results: Nineteen eyes were included in the IFCG group and 20 eyes in the BBG group. In all cases a FTMH closure was found. CDVA improved at 6 and 12 months in both groups (p < 0.0005); the increase at 12 months was greater in the BBG group (p = 0.036). EZ and ELM defects did not differ between groups at either follow-up time. CFT at 12 months was greater in the BBG group (p = 0.041). A 12-months compared to 6-months MT decrease was present in both groups (p < 0.01). The GCL++ superior inner sector was thicker in the BBG group at 12 months (p = 0.036), as were the superior outer sector (p = 0.039 and p = 0.027 at 6 and 12 months, respectively) and inferior outer sector (p = 0.011 and p = 0.009 at 6 and 12 months, respectively). Conclusion: In our study BBG in I-ILMFS exhibits better long-term CDVA and retinal thickness than does IFCG, suggesting a lesser toxicity from BBG. These findings support the use of BBG over IFCG in I-ILMFS.

Characterization of Prelaminar Wedge-Shaped Defects in Primary Open-Angle Glaucoma

PURPOSE

To determine the clinical relevance of prelaminar wedge defects (PLWDs) detected by swept-source optical coherence tomography (SS-OCT) in primary open-angle glaucoma (POAG).

MATERIALS AND METHODS

In this retrospective case-control study, PLWDs were defined as triangular-shaped defects at the surface of the optic nerve prelaminar tissue, not adjacent to blood vessels, present on cross-sectional SS-OCT scans. Two observers masked to diagnosis independently reviewed scans to detect PLWDs and lamina cribrosa defects. History of disc hemorrhage, occurring within 2 years prior to imaging, was obtained from chart review. One eye per subject was randomly selected. Two-sided t-tests, analysis of variance with Bonferroni correction, and multivariable logistic regression analysis were performed to explore demographic and clinical features associated with PLWDs.

RESULTS

40 POAG and 23 control eyes were included. PLWDS were found in 27.5% of POAG (n = 11) and 4.3% of controls (n = 1, p = .04). Eyes with repeat SS-OCT imaging (7 POAG and 0 controls) had persistent PLWDs. More POAG eyes with PLWDs had a history of disc hemorrhage (45.5%) than POAG eyes without PLWDs (3.4%, p = .004). On multivariable analysis, compared to POAG without PLWDs, POAG with PLWDs had increased odds of observed disc hemorrhage (OR = 21.6, 95% CI, 2.2-589.0, p = .02) after adjusting for age, gender, visual field mean deviation and maximum intraocular pressure (IOP). POAG with PLWDs had more lamina cribrosa defects (45.5%) than POAG without PLWDs (3.4%, p = .01) but did not differ significantly from controls (8.7%, p = .07). Compared to all patients without PLWDs, patients with PLWDs had increased odds of having lamina cribrosa defects (OR = 44.8; 95% CI, 6.3-703.6, p < .001) after adjusting for age, gender, and maximum IOP.

CONCLUSIONS

PLWDs were more frequently found in POAG than control eyes and were associated with a history of disc hemorrhage and lamina cribrosa defects. PLWDs may be a useful imaging biomarker of glaucomatous damage.

Diagnostic Validation of the Screening Corneal Objective Risk of Ectasia Analyzer Evaluated by Swept Source Optical Coherence Tomography for Keratoconus in an Asian Population

We aimed to investigate the diagnostic accuracy of Screening Corneal Objective Risk of Ectasia (SCORE) Analyzer software using ANTERION, a swept-source optical coherence tomography device, for keratoconus diagnosis in an Asian population. A total of 151 eyes of 151 patients were included in this retrospective study as follows: 60, 45, and 46 keratoconus, keratoconus suspects, and normal control eyes, respectively. Parameters in the SCORE calculation, including six indices, were compared for the three groups. The receiver operating characteristic curve analysis and cut-off value were estimated to assess the diagnostic ability to differentiate keratoconus and keratoconus suspect eyes from the normal group. The SCORE value and six indices were significantly correlated-"AntK max" (R = 0.864), "AntK oppoK" (R = 0.866), "Ant inf supK" (R = 0.943), "Ant irre 3mm" (R = 0.741), "post elevation at the thinnest point" (R = 0.943), and "minimum corneal thickness" (R = -0.750). The SCORE value showed high explanatory power (98.1%), sensitivity of 81.9%, and specificity of 78.3% (cut-off value: 0.25) in diagnosing normal eyes from the keratoconus suspect and keratoconus eyes. The SCORE Analyzer was found to be valid and consistent, showing good sensitivity and specificity for keratoconus detection in an Asian population.

Anterior Scleral Thickness Profile in Keratoconus

PURPOSE

Considering that peripheral corneal thinning occurs in keratoconus (KC), the anterior scleral thickness (AST) profile was measured to compare thickness variations in healthy and KC eyes across several meridians.

METHODS

This cross-sectional case-control study comprised 111 eyes of 111 patients: 61 KC eyes and 50 age- and axial-length-matched healthy eyes. The AST was explored at three scleral eccentricities (1, 2, and 3 mm from the scleral spur) across four scleral zones (nasal, temporal, superior, and inferior) by using swept-source optical coherence tomography. The AST variations among eccentricities and scleral regions within and between groups were investigated.

RESULTS

The AST significantly varied with scleral eccentricity in healthy eyes over the temporal meridian (p = 0.009), whereas in KC eyes, this variation was observed over the nasal (p = 0.001), temporal (p = 0.029) and inferior (p = 0.006) meridians. The thinnest point in both groups was 2 mm posterior to the scleral spur (p < 0.001). The sclera was thickest over the inferior region (control 581 ± 52 μm, KC 577 ± 67 μm) and thinnest over the superior region (control 448 ± 48 μm, KC 468 ± 58 μm) in both populations (p < 0.001 for all eccentricities). The AST profiles were not significantly different between groups (p > 0.05). The inferior-superior thickness asymmetry was statistically different 2 mm posterior to the scleral spur between groups (p = 0.009), specifically with subclinical KC (p = 0.03). There is a trend where the asymmetry increases, although not significantly, with the KC degree (p > 0.05).

CONCLUSIONS

KC eyes presented significant thickness variations among eccentricities over the paracentral sclera. Although AST profiles did not differ between groups, the inferior-superior asymmetry differences demonstrated scleral changes over the vertical meridian in KC that need further investigation.

Changes in Inner Retina Thickness and Macular Sensitivity in Patients with Type 2 Diabetes with Moderate Diabetic Retinopathy

The increase in diabetic retinopathy (DR) prevalence demonstrates the need for the determination of biomarkers for assessing disease development to obtain an early diagnosis and stop its progression. We aimed to analyse total retinal (RT) and inner retinal layer (IRL) thicknesses in type 2 diabetes mellitus (DM2) patients and correlate these results with retinal sensitivity using swept-source OCT (SS-OCT) and microperimetry. For this purpose, a total of 54 DM2 subjects with moderate diabetic retinopathy (DR) with no signs of diabetic macular oedema (DME) and 73 age-matched healthy individuals were assessed using SS-OCT to quantify retinal thickness in the nine macular areas of the ETDRS grid. Retinal sensitivity was measured via microperimetry with a Macular Integrity Assessment Device (MAIA). The mean ages were 64.06 ± 11.98 years for the DM2 group and 60.79 ± 8.62 years for the control group. DM2 patients presented lower visual acuity (p < 0.001) and a thicker RT (260.70 ± 19.22 μm in the control group vs. 271.90 ± 37.61 μm in the DM2 group, p = 0.01). The retinal nerve fibre layer (RNFL) was significantly lower in the outer nasal area (50.38 ± 8.20 μm vs. 45.17 ± 11.25 μm, p = 0.005) in ganglion cells and inner plexiform layers (GCL+) in DM2. A positive correlation between the LDL-C and RNFL and a negative correlation between HDL-C levels and the inner temporal and central RNFL thickness were detected. The central (p = 0.021) and inner nasal (p = 0.01) areas were negatively correlated between the RNFL and MAIA, while GCL++ was positively correlated with the outer inferior (p = 0.015) and outer nasal areas (p = 0.024). Retinal sensitivity and macular RNFL thickness decrease in DM2 patients with moderate DR with no DME, and this study enables an accurate approach to this disease with personalised assessment based on the DR course or stage. Thus, GCL+ and GCL++ thinning may support ganglion cell loss before the RNFL is affected.

Optical Coherence Tomography in Retinal Detachment: Prognostic Biomarkers, Surgical Planning, and Postoperative Monitoring

Retinal detachment (RD) is a vision-threatening ocular emergency that necessitates rapid diagnosis and intervention. This review examines the evolving role of optical coherence tomography (OCT) in RD by synthesizing the literature on preoperative biomarkers and advanced image modalities that inform diagnosis, prognosis, and surgical planning. We evaluated studies employing spectral-domain OCT, swept-source OCT, OCT angiography, adaptive optics OCT, and en face OCT to assess photoreceptor integrity, retinal detachment height, intraretinal cystic cavities, outer retinal corrugations and undulation, and macular involvement. The incorporation of OCT assessment into clinical practice may facilitate more precise surgical timing, technique selection, and postoperative monitoring. Further research is needed to standardize imaging protocols and validate specific prognostic biomarkers for optimal surgical outcomes. Key aspects include uniform imaging protocols, validating OCT-derived biomarkers such as ellipsoid zone integrity, and correlating OCT metrics with functional outcomes.