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.

Dry eye disease in students with myopia during COVID-19 pandemic

Background. Today, the urgent problem is coronavirus disease 2019 pandemic in the whole world. Safety measures such as the use of masks, distance learning have been implemented. However, ophthalmologists, as well as the general population, should know that a face mask together with prolonged use of digital devices leads to an increase in the number of dry eye cases in many patients. The purpose was to study the frequency of dry eye disease in students with myopia. Materials and methods. The study involved 96 medical students diagnosed with myopia taken by random sampling, who were examined by an ophthalmologist. Apart from the standard ophthalmologic examination, all patients underwent the evaluation of the stability of the precorneal tear film by means of corneal topography, and Norn test (tear break-up time (TBUT)). There was also used a standard questionnaire designed to assess the severity of dry eye disease symptoms (Ocular Surface Disease Index). Results. The corneal topography of the 47 patients did not demonstrate any reduction in TBUT. The average time of the concentric ring remained stable for 20.2 ± 3.0 seconds. But 49 individuals exhibited signs of tear film instability over time compared to 47 patients without TBUT impairment. In 47 people without impairments, corneal topography demonstrated that this indicator in Norn test varied from 25 to 18 seconds, i.e. was within the age norm (21.5 ± 3.5 seconds on average). In 3 patients with a minimum TBUT on keratotopography, its value during the Norn test was 9 seconds. In 36 patients with reduced TBUT according to both methods, there was a weak degree of dry eyes, in 10 — moderate, in 3 — severe. The most common complaints were a sandy, gritty sensation in the eyes, visual discomfort when working at a computer and in windy weather, and with prolonged use of a protective mask. Conclusions. Among students who were on distance learning, 51.04 % of individuals have objectively confirmed dry eye disease. People wearing contact lenses have a more pronounced degree of dry eye, so it is mandatory for ophthalmologists to prescribe lubricating eye drops.

Diagnostic Accuracy of Anterior Segment Optical Coherence Tomography Pachymetry Mapping and Detection for Early Keratoconus using Corneal Topography as Gold Standard

Background: Optical coherence tomography (OCT) derived pachymetry mapping has potential in diagnosis of early and advancing keratoconus. The OCT corneal pachymetry map–based logistic regression formula and the keratoconus risk scoring system has been proven to provide very accurate results in keratoconus identification. In keratoconus screening these techniques might be helpful. Objectives: To ascertain the diagnostic accuracy of anterior segment optical coherence tomographic corneal pachymetry to diagnose the cases the cases of early keratoconus by using corneal topography as a high standard with which other techniques of these kinds are compared. Study Design: Cross-sectional (validation) study. Duration: One year from July 01, 2019 to June 30, 2020. Settings: Department of Ophthalmology, Allied Hospital/DHQ Hospital, Faisalabad Pakistan. Methodology: A total of 195 patients having asymmetrical astigmatism (>1 diopter), 12-40 years of age of both genders were included. Patients with corneal ulcer and corneal opacity were excluded. After complete examination corneal topography and anterior segment optical coherence tomography was performed. Tomographic minimum central corneal thickness was recorded and assessed for cutoff value, if exceeding cutoff value patient was diagnosed with the early keratoconus. Results: In OCT pachymetry positive patients, 103 (True Positive) had early keratoconus and 05 (False Positive) had no early keratoconus on corneal topography. Among 87, OCT pachymetry negative patients, 04 (False Negative) had early keratoconus on corneal topography whereas 83 (True Negative) had no early keratoconus on corneal topography (p=0.0001). Overall sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of anterior segment optical coherence tomographic corneal pachymetry to diagnose the cases of early keratoconus in the suspected individuals by using corneal topography as gold standard was 96.26%, 94.32%, 95.37%, 95.40% and 95.38% respectively. Conclusion: This study concluded that diagnostic accuracy of anterior segment optical coherence tomographic corneal pachymetry to find out the cases of early keratoconus is very high. Keywords: Optical coherence tomographic corneal pachymetry, Keratoconus, Sensitivity

The treatment zone size and its decentration influence axial elongation in children with orthokeratology treatment

Background To investigate whether the treatment zone size (TZS) and treatment zone decentration (TZD) will affect the axial elongation in myopic children undergoing orthokeratology treatment. Methods A self-controlled retrospective study was conducted on 352 children who met the inclusion criteria. Axial length was measured before and at 12 months after the initial lens wear. Corneal topography was measured at baseline and at each follow-up after lens wear. The Corneal topography obtained from the 12-month visit was used to quantify TZS and TZD for each subject. Cycloplegic refraction was required for all children before fitting the orthokeratology lenses. Results Axial elongation was significantly associated with age, baseline spherical equivalent (SE), TZS, and TZD with univariate linear regression. In groups with both small and large TZS, axial elongation was significantly decreased with large TZD (both P < 0.01). In groups with both small and large TZD, axial elongation was significantly decreased with small TZS (P = 0.03 for small TZD, P = 0.01 for large TZD). Age, SE, and TZD were significantly associated with axial elongation in multiple regression (all P < 0.01). Conclusion Relatively smaller TZS and larger TZD may be beneficial in slowing myopia progression in children with orthokeratology treatment.

Diagnosability of Keratoconus Using Deep Learning With Placido Disk-Based Corneal Topography

Purpose: Placido disk-based corneal topography is still most commonly used in daily practice. This study was aimed to evaluate the diagnosability of keratoconus using deep learning of a color-coded map with Placido disk-based corneal topography.Methods: We retrospectively examined 179 keratoconic eyes [Grade 1 (54 eyes), 2 (52 eyes), 3 (23 eyes), and 4 (50 eyes), according to the Amsler-Krumeich classification], and 170 age-matched healthy eyes, with good quality images of corneal topography measured with a Placido disk corneal topographer (TMS-4TM, Tomey). Using deep learning of a color-coded map, we evaluated the diagnostic accuracy, sensitivity, and specificity, for keratoconus screening and staging tests, in these eyes.Results: Deep learning of color-coded maps exhibited an accuracy of 0.966 (sensitivity 0.988, specificity 0.944) in discriminating keratoconus from normal eyes. It also exhibited an accuracy of 0.785 (0.911 for Grade 1, 0.868 for Grade 2, 0.920 for Grade 3, and 0.905 for Grade 4) in classifying the stage. The area under the curve value was 0.997, 0.955, 0.899, 0.888, and 0.943 as Grade 0 (normal) to 4 grading tests, respectively.Conclusions: Deep learning using color-coded maps with conventional corneal topography effectively distinguishes between keratoconus and normal eyes and classifies the grade of the disease, indicating that this will become an aid for enhancing the diagnosis and staging ability of keratoconus in a clinical setting.

Central Corneal Thickness of Syrian Population in Relation to Different Parameters: ثخانة القرنية المركزية لِعيّنة من المواطنين السورييّن وعلاقتها مع المتغيّرات المختلفة

Objectives: The aim of this study is to determine the mean Central Corneal Thickness (CCT) among a normal Syrian population and to correlate between Central Corneal Thickness and age, gender and axial length. Methods: This study was carried out at Tishreen University Hospital in Latakia. A total of 516 eyes from 258 individuals with an age range from 18 to 56 years were studied. Central Corneal Thickness was measured using corneal topography (SIRIUS). Axial length was measured using contact ultrasound A-scan (AVISO). Results: The mean CCT was 546.7±31.2 µm with a range from 456 to 643 µm. CCT was not affected by gender. CCT significantly negatively correlated with age (p=0.001). There was no statistically significant correlation between CCT and axial length (p=0.6). Conclusions: CCT varies according to race. Among a Syrian population, CCT significantly decreased with age.