Serpiginous Choroiditis Complicated with Choroidal Neovascular Membrane Detected using Optical Coherence Tomography Angiography: A Case Series and Literature Review

Serpiginous choroiditis (SC) is a rare, chronic, recurrent, progressive disease of unknown origin. The inflammatory process of SC can disrupt Bruch's membrane, allowing occasional choroidal vascular growth, leading to significant visual loss even in the healed stages of the disease. Optical coherence tomography angiography (OCTA) can help in the detection of choroidal neovascular membrane (CNV), leading to a definitive diagnosis and thereby guide the initiation of intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment. We report herein two cases of SC complicated with a CNV detected with OCTA and treated with a series of anti-VEGF injections.

Comparison of Subthreshold 532 nm Diode Micropulse Laser with Conventional Laser Photocoagulation in the Treatment of Non-Centre Involved Clinically Significant Diabetic Macular Edema.

BACKGROUND: The aim of the study was to investigate the effect of the 532 nm (green) diode subthreshold micropulse laser (SML) in the treatment of non-centre involved clinically significant macular edema (CSME) in comparison to the conventional laser photocoagulation (CLP). METHODS: A total of 60 eyes of patients diagnosed with non-centre involved CSME were randomly divided into two groups. SML photocoagulation was performed in the first group (G1), while CLP in the second one (G2). Central macular thickness (CMT) and best corrected visual acuity (BCVA) were measured prior to treatment and at 3 and 6 months after intervention. RESULTS: G1 participants had significantly better CMT at 6 months after laser application (p = 0.04) compared to G2. Additionally, CMT in both groups was significantly lower 6 months after laser application in comparison to baseline values (G1: p < 0.001, G2: p = 0.002). Moreover, significant improvement was detected 6 months after SML in G1 regarding BCVA compared to values before laser treatment (p = 0.001). CONCLUSION: SML was more effective than CLP in reducing CMT and improving BCVA in patients with non-centre involved CSME. Therefore, it seems that SML can be a good substitute for CLP in DME treatment if confirmed in future studies.

Level of agreement of intraocular lens power measurements between an image-guided system and partial coherence interferometry.

PURPOSE: To evaluate the level of agreement of partial coherence interferometry (IOLMaster) and an image-guided system (Verion) in terms of keratometric values and intraocular lens (IOL) power calculation. SETTING: Department of Ophthalmology, University Hospital of Alexandroupolis, Greece. DESIGN: Prospective comparative study. METHODS: Keratometric (K) values and IOL power calculations were compared for 3 toric IOL models (SN6ATx, TFNTx0, and SV25Tx) using 4 formulas (SRK/T, Holladay 1, Hoffer Q, and Haigis) in patients who had cataract surgery in a consecutive-if-eligible way. RESULTS: Ninety-eight eyes from 54 patients were included in the study (mean age: 60.2 ± 9.2 years). Compared with the IOLMaster, the Verion measured significantly steeper K1, K2, and Km values (P < .05), but no significant difference was observed in astigmatism power and vectors J0 and J45 (P > .05). With the SRK/T formula, the SN6ATx IOL showed significant difference in the mean IOL power calculated by the 2 devices, whereas no significant difference was observed in the TFNTx0 IOL and the SV25Tx IOL. However, with the Holladay 1, Hoffer Q, and Haigis formulas, a significant difference was found in the mean IOL power of all 3 toric IOL models. Generally, the Verion calculated a significantly lower mean IOL power for almost all formulas and IOL models. For 35 toric implantations, the mean residual astigmatism power, 6 months postoperatively, was 0.29 ± 0.24 diopter. CONCLUSIONS: The IOLMaster and the Verion seemed to present differences in IOL calculation and surgical planning that could lead to unexpected residual refractive error. When discrepancy is detected in IOL calculation, using the IOLMaster as the primary biometry and the Verion as a digital marker alone could provide excellent outcomes in terms of astigmatism correction.

Image-guided lens extraction surgery: a systematic review.

A systematic review of the recent literature regarding the current image-guided systems used for cataract surgery or refractive lens exchange was performed based on the PubMed and Google Scholar databases in March 2018. Literature review returned 21 eligible studies. These studies compared image-guided systems with other keratometric devices regarding their accuracy, repeatability and reproducibility in measurement of keratometric values, astigmatism magnitude and axis, as well as in IOL power calculation. Additionally, the image-guided systems were compared with conventional manual ink-marking techniques for the alignment of toric IOLs. In conclusion, image-guided systems seem to be an accurate and reliable technology with measurements of high repeatability and reproducibility regarding the keratometry and IOL power calculation, but not yet interchangeable with the current established and validated keratometric devices. However, they are superior over the conventional manual ink-marking techniques for toric IOL alignment.

Impact of light conditions on reading ability following multifocal pseudophakic corrections.

PURPOSE: To examine the impact of light intensity and temperature on reading performance following bilateral pseudophakic multifocal presbyopic correction. PATIENTS AND METHODS: This is a prospective clinic-based trial conducted at the Department of Ophthalmology in the University Hospital of Alexandroupolis, Greece. Three groups of patients were formed (G1: patients with bilateral bifocal implantation, G2: patients with bilateral trifocal implantation, and control group: patients with bilateral pseudophakic monofocal implantation). Reading ability was quantified with the Greek version of MNREAD chart with minimal reading speed at 80 words/min for the following light intensities (25, 50, and 75 Foot-Candles [FC]) and temperatures (3,000, 4,000, and 6,000 K). Preferred light conditions for reading were assessed, as well. ClinicalTrials.gov Identifier: NCT03226561. RESULTS: Control group demonstrated significantly lower reading ability at all light combinations with maximal ability at 75 FC and 6,000 K (0.58±0.18 logMAR). Bifocal group presented a light-dependent reading ability that ranged from 0.45±0.08 logMAR (25 FC and 3,000 K) to 0.40±0.11 logMAR (75 FC and 4,000 or 6,000 K). Trifocal participants presented the best reading ability that was light intensity-independent; however, their performance was reduced at 6,000 K. G1 and G2 preferred primarily intermediate light temperature, while control participants preferred cold light temperature. CONCLUSION: Multifocal pseudophakic corrections improve reading ability; however, they present variable efficacy according to the light conditions.

Effect of Riboflavin/UVA Collagen Cross-linking on Central Cornea, Limbus and Intraocular Pressure. Experimental Study in Rabbit Eyes.

The Purpose of present study was to investigate the effect of riboflavin/ultraviolet-A-induced collagen cross-linking (CXL) on central cornea, limbus and intraocular pressure (IOP). This was an animal experimental study. The right corneas of 10 rabbits were ultraviolet-A irradiated (3 mW/cm2 for 30 minutes) after de-epithelialization and instillation of 0.1% riboflavin / 20% Dextran drops. Left corneas served as controls. Samples were examined histologically one month postoperatively. Before and after treatment, IOP measurements were recorded bilaterally. At central cornea of eyes underwent CXL keratocyte repopulation, normal arrangement of collagen fibres and a statistically significant change in fibres diameter were detected, compared to controls. At limbus area, there were not any significant histological differences after CXL. There was no statistically significant difference between pre- and postoperative IOP in all eyes.

Liquefaction for cataract extraction.

A systematic review of the recent literature regarding the implementation of the liquefaction in cataract surgery and its short-term and long-term outcomes in various parameters that affect the quality of patients' life, including visual rehabilitation and possible complications was performed based on the PubMed, Medline, Nature and the American Academy of Ophthalmology databases in November 2013 and data from 14 comparative studies were included in this narrative review. Liquefaction is an innovative technology for cataract extraction that uses micropulses of balanced salt solution to liquefy the lens nucleus. Most studies reported that liquefaction is a reliable technology for mild to moderate cataracts, while fragmentation difficulties may be encountered with harder nuclei.

Corneal biomechanical properties and anterior segment parameters in forme fruste keratoconus.

PURPOSE: To evaluate the sensitivity and specificity of corneal biomechanical metrics, anterior segment data, and a combination model in differentiating forme fruste keratoconus (FFK) from normal corneas. METHODS: A total of 50 FFK eyes were identified by calculation of the KISA index and recruited FFK group. Results were compared with 50 normal eyes (NG group) randomly selected from 50 patients. The following parameters were evaluated for their diagnostic capacity by evaluation of their receiver operating characteristic curves (ROC): corneal hysteresis (CH), corneal resistance factor (CRF), corneal astigmatism (Cyl), anterior chamber depth (ACD), corneal volume (CV) at 3 mm (CV3) and at 5 mm (CV5), maximum posterior elevation value (PEL), central corneal thickness (CCT), thinnest corneal thickness (TCT) and its coordinates (TCTx, TCTy ), the ratio TCT/CCT, pachymetric progression indexes (PPImin, PPIavg, and PPImax), and Ambrósio's relational thickness (ARTmin, ARTavg, and ARTmax). Logistic regression was attempted for identification of a combined diagnostic model. RESULTS: Significant differences were detected in all studied parameters except the Cyl, ACD, TCTx, and CV. Among individual parameters, the highest predictive accuracy was for ARTavg (area under the curve [AUC] 95.4%, sensitivity 90%, specificity 88.9%) and TCT (AUC 95.3%, sensitivity 90.9%, specificity 89%). Sufficient predictive accuracy (AUC 99.4%, sensitivity 98.8%, specificity 94.6%) was identified in a diagnostic model that combined the CRF, ARTavg, and PEL parameters. CONCLUSIONS: None of the individual parameters provide sufficient diagnostic capacity in FFK. However, diagnostic models that combine biomechanical and tomographic data seem to provide high accuracy in differentiating FFK from normal corneas.

Impact of keratoconus, cross-linking and cross-linking combined with photorefractive keratectomy on self-reported quality of life.

PURPOSE: To assess the effect of stage 1 keratoconus (KC) and of the 2 prevalent KC therapeutic options: (1) corneal collagen cross-linking (CXL) and (2) CXL combined with topography-guided photorefractive keratectomy (t-PRK) on self-reported quality of life (QOL) by means of the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ 25). METHODS: Thirty-two patients with bilateral KC stage 1 (KC group) and best-corrected visual acuity of 20/20 in both eyes were prospectively recruited. Of them, 19 KC patients underwent typical CXL treatment (CXL group), whereas 13 underwent CXL combined with t-PRK treatment (tCXL group). Only the eye with the most advanced condition received the treatment. Subjects responded to the NEI-VFQ 25 1 day before the treatment and 1 year postoperatively. Thirty-nine age-matched contact lens users formed the control group. NEI-VFQ 25 subscale and total scores were associated with spherical equivalent, mean keratometry, and a series of Scheimpflug imaging-derived corneal variance indexes by means of the Spearman correlation coefficient and multivariate linear regression analysis. RESULTS: Preoperatively, significant differences were detected between the KC group and the control group in VFQ 25 total and all subscale scores (P < 0.05), except "general health," "color vision," and "peripheral vision" domains. According to the multivariate linear regression analysis, the index of height decentration was the most significant predictor of VFQ 25 total score (b = 0.943; P = 0.016). Postoperatively, significant differences were detected in "mental health" and "dependency" VFQ 25 domains for both the CXL and tCXL groups (P = 0.05). Furthermore, the tCXL group demonstrated significant differences in the "near activities" (P = 0.04), "role limitations" (P = 0.02), and "driving" (P < 0.01) subscale scores. CONCLUSIONS: Our results suggest that KC exerts a significant impact on KC patients' QOL, even in its early stages with normal best-spectacle-corrected visual acuity. Moreover, both CXL and CXL combined with t-PRK seem to exert a beneficial impact on self-reported QOL, suggesting that they should be applied as soon as possible.

Tonometry in keratoconic eyes before and after riboflavin/UVA corneal collagen crosslinking using three different tonometers.

PURPOSE: To evaluate the Goldmann applanation tonometer (GAT), the Pascal dynamic contour tonometer (PDCT), and the ocular response analyzer (ORA) tonometer in measuring intraocular pressure (IOP) in keratoconic eyes before and after riboflavin/ultraviolet A corneal collagen crosslinking (CXL), to assess agreement among devices and to analyze the impact of some ocular parameters on their measurements. METHODS: Fifty keratoconic eyes were included. Intraocular pressure was measured with GAT, PDCT, and ORA before and after CXL. Fifty nonkeratoconic eyes served as controls. Device agreements were calculated by Bland-Altman analysis. The effect of some ocular characteristics on IOP measurement differences between tonometers was determined. RESULTS: Between the 2 groups, there were statistically significant differences in all examined parameters. Preoperatively, in both groups a statistically significant difference was found in IOP measurements among devices (p<0.05). Bland-Altman analysis showed a bias among devices. On average, PDCT overread GAT and ORA. The IOP measurement differences were better predicted by corneal resistance factor. Postoperatively, in keratoconus eyes, there was no statistically significant difference in IOP measurements among the 3 tonometers (p>0.05). The IOP readings with all tonometers after treatment were higher than those obtained preoperatively; however, not to a statistically significant level, with the exception of PDCT and ORA readings at the first month postoperatively. Corneal resistance factor measurements have no significant change after CXL. CONCLUSIONS: Pascal dynamic contour tonometer could provide more consistent and closer to the true IOP readings than GAT and ORA in healthy eyes with corneal thickness outside the 520-550 µm range, in keratoconus patients and after CXL. Corneal resistance factor was associated significantly with agreement among devices.

Psychometric properties of the Greek NEI-RQL-42.

PURPOSE: To evaluate the psychometric properties of the Greek National Eye Institute Refractive Error Quality of Life Questionnaire (NEI-RQL-42). METHODS: We developed the Greek version of the instrument using forward and backward translation. To examine reliability, Cronbach alpha for each subscale was used as an index of internal consistency. Test-retest reliability was evaluated with intraclass correlation coefficients (ICC). Regarding construct validity, both convergent and discriminant validities were calculated by means of multi-trait analysis. Furthermore, the instrument was evaluated by Rasch analysis, as well. RESULTS: Three patient groups were studied (emmetropes (n = 20), myopes (n = 41), and hyperopes (n = 18)). Emmetropes scored significantly better in the majority of subscales, while myopes scored better than hyperopes in clarity of vision (p = 0.012), near vision (p<0.001), and satisfaction with correction (p = 0.001). Cronbach alpha ranged from 0.490 (glare) to 0.948 (expectations), with most subscales having high internal consistency. The ICCs ranged from 0.76 to 0.93 for all subscales. All items passed the convergent and discriminant validity tests. Strong correlations were detected between uncorrected visual acuity and near vision, expectations, activity limitations, dependence on correction, worry, and suboptimal correction subscales. Rasch analysis revealed potential weaknesses of the instrument that are associated with the assumptions of the model itself. Specifically, 3 items and 17.5% of the participants fell outside the tolerance box. Moreover, principal component analysis indicated average unidimensionality for the instrument. CONCLUSIONS: Traditional validation methods indicate that the Greek NEI-RQL-42 scale has adequate psychometric properties for comparative studies in local populations. Rasch analysis indicates significant misfits to the model that should be taken into consideration and evaluated in future studies. These misfits might reflect inherent weaknesses of the original NEI-RQL-42 and not of its adaptation to Greek norms.

Evaluation of corneal hysteresis and corneal resistance factor after corneal cross-linking for keratoconus.

BACKGROUND: To evaluate corneal hysteresis (CH) and corneal resistance factor (CRF) in keratoconic (KC) eyes before and after corneal collagen cross-linking (CXL). Furthermore, to determine potential correlations with a series of corneal and demographic factors. METHODS: The study consisted of 50 KC eyes that underwent CXL. CH and CRF were measured by the ocular response analyzer (ORA). Correlations were attempted with uncorrected visual acuity (UVA), best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), mean keratometry (Km), astigmatism (Astig.), residual astigmatism, age, and gender. Fifty non-KC eyes served as controls. RESULTS: CH and CRF (mean ± SD) for non-KC eyes were 10.1 ± 1.9 mmHg and 9.7 ± 2.4 mmHg respectively, while for KC eyes preoperatively they were 8.2 ± 1.4 mmHg (p = 0.007) and 7.4 ± 2.3 mmHg (p = 0.01) respectively. Non-significant differences were detected between preoperative and postoperative CH and CRF measurements in KC eyes (p = 0.518 and p = 0.479 respectively). Significant correlations were found between ORA parameters and BSCVA, CCT, Km, Astig. and residual astigmatism. CONCLUSIONS: ORA parameters demonstrate significant differences between KC and non-KC eyes. Both CH and CRF present significant correlations with visual acuity and corneal parameters. CXL exerts a non-significant impact on ORA measurements.

Corneal collagen cross-linking using riboflavin and ultraviolet-A irradiation: a review of clinical and experimental studies.

Corneal collagen cross-linking (CXL) using riboflavin and ultraviolet-A irradiation is a common method of tissue stabilization and has been developed primarily to address the need of treating keratoconus. CXL's promising results on keratoconus indicated that it might be effective in other corneal diseases as well. This new treatment promises a slowing effect on the progression of these diseases and its initial results show that it is safe and reasonably curative. The purpose of this review is to critically evaluate this treatment, to explore its benefits, to highlight its limitations in terms of efficacy and long-term safety and finally to identify areas for future research in this topic with a significant potential to change the way we treat our patients. In addition, in this unbiased review we try to bring together all the scientific information from both laboratory and clinical trials that have been conducted during recent years and to review the most recent publications regarding the therapeutic indications of CXL.

Additional applications of corneal cross linking.

Corneal collagen cross-linking (CxL) is a prevalent surgical method for the management of keratoconus. However, literature suggests that, further to keratoconus, CxL has a beneficial impact on a series of corneal related diseases and states. This article attempts to provide a contemporary review for all additional applications of CxL. Specifically, it outlines the most recent studies that demonstrate the beneficial impact of CxL for iatrogenic ectasias, pellucid marginal degeneration, infectious keratitis, bullous keratitopathy, and for ulcerative keratitis. The outcome of this review indicates that CxL could serve as a primary or adjuvant therapeutic modality for all aforementioned corneal-related pathologic states.

Reproducibility of OCT/SLO measurements in healthy eyes.

PURPOSE: To determine the reproducibility of optical coherence tomography/scanning laser ophthalmoscope (OCT/SLO) measurements within and between observers and within and between sessions in healthy eyes. METHODS: Forty eyes of 40 healthy volunteers recruited from the outpatient service of the Department of Ophthalmology at the University Hospital of Alexandroupolis, Greece, were included. Retinal thickness scans were performed 3 times by two experienced operators within each of 3 sessions, which took place within a month, using the spectral OCT/SLO. The OCT/SLO provides retinal nerve fiber layer (RNFL) thickness and volume measurements and a 3D tomography analysis of optic nerve head. Statistical analysis was conducted using Bland-Altman plots, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). RESULTS: As shown by the CoV values, RNFL parameters were generally found to have high reproducibility (CoV ranging from 4.3% to 10.9% for both operators), whereas optic disc parameters had scores reaching up to 22.5%. On the other hand, as shown by the ICC values, intraobserver and interobserver reproducibility for the OCT/SLO was high for optic disc parameters but low for RNFL thickness and volume measurements. Interobserver reproducibility was found to be highest for the maximum cup depth parameter and lowest for the superior volume. Bland-Altman plots indicate that bias is minimal for practically all parameters and scatterplot homoscedasticity is high. CONCLUSIONS: According to our data, SLO/OCT generally has a good reproducibility profile, as differences between the two operators were small. However, additional studies on the reproducibility of measurements with the OCT/SLO are needed.

UV-A Collagen Cross-Linking Treatment of Bullous Keratopathy Combined With Corneal Ulcer.

PURPOSE: To evaluate the therapeutic effect of corneal cross-linking (CXL) in 2 cases of bullous keratopathy combined with corneal ulcer. METHODS: Two patients (2 eyes) were recruited for the sake of the study. Both suffered from bullous keratopathy and presented a gradually deteriorating, vision-threatening, central corneal ulcer, despite intense local antibiotic therapy. The same surgical procedure was performed in both eyes. De-epithelialization of the affected corneas was accompanied by UV-A cross-linking and finally by the application of a therapeutic contact lens. Local antibiotic therapy was resumed after the procedure. RESULTS: Within 24 hours of the treatment, both patients reported significant subjective improvement of their visual acuity and ocular discomfort. Clinical evaluation revealed improvement of the corneal ulcer and the bullous keratopathy associated with significant decrease of the corneal thickness and haziness. During the 2-month follow-up period, a significant improvement of visual acuity was recorded in both cases. CONCLUSION: CXL should be considered as a potential adjuvant therapeutic tool in patients with combined bullous keratopathy and infectious keratitis, who are resistant to traditional topical therapy.

Anterior chamber volume measurements with Visante optical coherence tomography and Pentacam: repeatability and level of agreement.

BACKGROUND: The purpose of this study is to examine the repeatability of Pentacam-derived anterior chamber volume measurements, and assess the level of agreement of anterior chamber volume measurements obtained with the Visante and the Pentacam imaging devices. METHODS: Anterior chamber volume was calculated with the Pentacam device and the Visante using the Wang formula. Results were analysed by means of the Wilcoxon signed rank test, Bland-Altman analysis, Cronbach's alpha test and intraclass correlation coefficient. P-values <0.01 were considered statistically significant. RESULTS: One randomly selected eye from each of 20 persons was analysed. Spherical equivalent ranged between -2.50 and +1.50 D, and their age ranged from 25 to 79 years (mean +/- SD: 54.4 +/- 19.2 years). Mean anterior chamber volume measured with Pentacam was 171.1 +/- 39.6 microL (minimum: 103.0 microL, maximum: 236.0 microL), and mean anterior chamber volume measured by Visante was 171.4 +/- 42.4 microL (minimum: 96.4 microL, maximum: 245.5 microL). There was no statistically significant difference between Pentacam and Visante measurements of the anterior chamber volume (P = 0.691, Wilcoxon signed rank test). Cronbach's alpha and intraclass correlation coefficient for Pentacam were 0.998 and 0.991, respectively. CONCLUSIONS: Anterior chamber volume measurements obtained with the Visante using the Wang formula were in good agreement with the corresponding ones obtained with Pentacam. This recently described method is easy to perform and might contribute to both clinical and research settings.