Medical hypothesis, discovery & innovation in optometry

Background: This study aimed to evaluate the clinical characteristics and changes in the number of patients receiving intravitreal injections (IVIs) at a tertiary hospital during the coronavirus disease 2019 (COVID-19) pandemic as compared to the pre-pandemic period.
Methods: This retrospective, cross-sectional study included 3,211 patients with retinal disease, who received IVIs of anti-vascular endothelial growth factor (anti-VEGF) between January and May 2020. This 5-month period was divided into a pre-pandemic and a pandemic period. Clinical and demographic data were collected and were compared between the patients in each period. All COVID-19 infection precautions were implemented to minimize the potential transmission of COVID-19 to both healthcare workers and patients.
Results: A total of 3,211 IVIs were administered to patients with diabetic retinopathy, age-related macular degeneration, retinal vein occlusion, and other retinal conditions. Diabetic retinopathy was the most common indication for treatment in the pre-pandemic as well as pandemic periods. Bevacizumab (Avastin, Roche) was the most common IVI type, followed by aflibercept (Eylea, Bayer). Of 3,211 IVIs, 2,943 (91.7%) were administered during the pre-pandemic period and 268 (8.3%) during the pandemic period. There was a statistically significant decrease in injections between the pre-pandemic and pandemic periods, with an overall reduction of 90.8% in IVIs (P < 0.05). No cases of confirmed transmission of COVID-19 orcomplications associated with IVIs were recorded.
Conclusions: This study showed that the number of IVIs and patient visits decreased significantly, by more than 10-fold, during the lockdown period. These findings show that COVID-19 has turned the management of sight-threatening eye diseases into a challenging process and must be addressed if future healthcarerestrictions are imposed.

Background: The Lenstar LS 900 (Haag-Streit AG, Koeniz, Switzerland) is an optical biometer, and its measurements are highly repeatable and precise in cataractous eyes. This study investigated changes in biometric parameters, including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), vitreous cavity depth (VD), and central corneal thickness (CCT) before and after three-port 23-Gauge pars plana vitrectomy with silicone oil tamponade.
Methods: This was a prospective follow-up study. Patients who were scheduled for surgery underwent a detailed slit-lamp examination and objective cycloplegic refraction preoperatively. In eligible cases, the Lenstar LS 900 was used to measure biometric parameters. At the 1-month postoperative follow-up, we repeated the same assessments for the silicone oil (SO)-filled eyes. Data were analyzed to assess the significance of changes and to test the possible correlation of values between the two time points.
Results: Twenty-three patients with a mean ± SD age of 60 ± 12 years completed the study. Postoperatively, we found a significant increase in AL and a decrease in ACD and CCT (all P < 0.05), with no significant changes in LT and VD. A significant correlation was found for ACD, CCT, and cylinder values between the two time points (all P < 0.05). Postoperatively, the spherical and cylindrical components of refraction demonstrated a hyperopic shift, but did not change statistically significantly.
Conclusions: The Lenstar LS 900 underestimated the ACD and overestimated the AL in SO-filled eyes when comparing pre- and postoperative values, in phakic as well as pseudophakic eyes. In planning for cataract surgery in this group of patients, it is more reasonable to calculate IOL power based on the biometric data of the fellow eye, although this may not eliminate possible errors. Further studies with a larger sample size, longer follow-up, and robust study design are necessary to confirm our preliminary results.

Background: Measuring contrast sensitivity (CS) allows a better understanding of the visual performance of the human eye. This study aimed to examine the correlation and agreement between the results of two sinewave grating-based CS measurement methods, Metrovision and CSV-1000, in normal eyes.
Methods: This cross-sectional, comparative study was performed between December 2018 and April 2019, at an optometry clinic. Subjects underwent comprehensive ocular examinations, which included pupil reflexes, subjective refraction, external eye examinations, smooth pursuit eye movement assessment, the cover–uncover test, and detailed slit-lamp examination of the anterior and posterior segments. Metrovision and CSV-1000 were employed to assess CS under photopic conditions. The correlation and agreement of the results of the two tests were evaluated.
Results: CS was measured for 104 normal eyes for 3, 6, 12, and 18 cycles per degree (cpd) spatial frequencies (participants’ mean age ± standard deviation: 37.3 ± 26.4 years). The CSV-1000 measurements were significantly higher for the 3 and 6 cpd spatial frequencies (both P = 0.01); however, at higher spatial frequencies, CS scores were similar. The highest and lowest differences between the two tests were recorded for the 3 cpd spatial frequency and 18 cpd spatial frequency, respectively. Except for the 3 cpd spatial frequency, in both eyes, the findings correlated significantly between the CSV-1000 and Metrovision (P < 0.05). The narrowest and widest limits of agreement between the two tests were found for the 12 and 3 cpd spatial frequencies, respectively.
Conclusions: The CSV-1000 method estimated CS higher than the Metrovision method, mostly at lower spatial frequencies. Furthermore, the agreement between the two methods was greater at higher spatial frequencies than at lower frequencies. This should be kept in mind when using the two methods interchangeably in visual screening.

Background: The mainstay of dry eye treatment is artificial tear solutions. Contralateral eye comparison of 2 types of artificial tears (Xiloial; tamarind seed polysaccharide-containing lubricant eye drop versus Tearlose) in managing dry eye disease was sought in this study.
Methods: This study was a prospective, interventional, contralateral eye comparison of 2 types of artificial tears used for managing dry eye disease. The study participants were categorized into mild (13–22 points), moderate (23–32 points), or severe (33–100 points) ocular surface disease according to the baseline ocular surface disease index (OSDI) questionnaire score. Schirmer I and tear film break-up time (TBUT) tests, as well as detailed slit-lamp examinations, were performed at baseline and at the end of the study. All participants received Xiloial monodose eye drops for the right eye and Tearlose eye drops for the left eye, administered as a single drop 4 times per day. Furthermore, they were instructed to perform lid hygiene every 12 hours per day for both eyes.
Results: Thirty-five patients (70 eyes) with a mean ± standard (SD) age of 50.2 ± 13.4 years were included, and 14 (40%) were men. The mean ± SD of the OSDI score was 44.24 ± 22.59 at baseline. Of the 35 patients, 10 (28.6%), 5 (14.3%), and 20 (57.1%) had mild, moderate, and severe ocular surface disease, respectively, according to the baseline OSDI score. Compared to baseline, the mean values of both TBUT and Schirmer I tests improved significantly in both groups (both P < 0.001). In comparing the final mean values between the 2 groups, this improvement was comparable for the Schirmer I test (P = 0.179), but TBUT in Tearlose-instilled eyes improved significantly more than in the fellow eyes (P < 0.001).
Conclusions: Both Xiloial and Tearlose eye drops improved tear stability and tear production after a 2 week treatment period in eyes with dry eye disease. This improvement was comparable for tear production, but Tearlose-instilled eyes showed significantly greater improvement in tear stability. Further studies with longer follow-up and larger sample sizes could provide more reliable results as a basis for the clinical use of this TSP-containing lubricant eye drop solution in dry eye disease.

Background: Many recent studies have focused on the potential hazards of blue light exposure to ocular health. One group with a unique blue light exposure risk is dentists, who use curing lights that emit intense blue light during restorative procedures. During these procedures, dentists often experience brief ocular exposure to these lights. The purpose of the present study was to explore whether such exposures may have an effect on the vision and ocular health of dentists.
Methods: A group of 12 dentists who had experienced curing light exposure over a period of 10 or more years were compared to a group of eight control subjects with no such exposure. The subjects were tested for visual acuity and contrast sensitivity. Their retinas were examined using fundus imaging and optical coherence tomography. Macular pigment optical density was measured. The likelihood that brief blue light exposure could lead to ocular effects was further explored by subjecting a retinal pigment epithelial cell (RPE) line to such exposures.
Results: Although no visual defects or ocular pathologies were found in either group, the dentist group differed from the control group in having increased macular thickness (P < 0.02), a higher incidence of macular vessel tortuosity (P < 0.05), and greater variance in their macular pigment optical density values (P < 0.01). RPE cells that received blue light exposure similar to those sustained by dentists demonstrated a change in physiology.
Conclusions: Retinal changes were found in dentists, which, while not pathological in themselves, are associated with some retinal pathologies. Further studies are necessary to determine whether these signs correlate with the degree of curing light exposure and to determine whether they eventually develop into pathological conditions.

Background: Dyslexia is a key learning disorder associated with reading difficulties in children. The purpose of this study was to determine the effectiveness of simple visual devices in improving the reading performance of children with dyslexia.
Methods: A case control study was conducted by selecting 80 school children with dyslexia, aged 8 to 11 years, from the Special Dyslexic School Program of the Ministry of Education (MOE) Malaysia. Subjects were randomly assigned to four groups: the typoscope, magnifier, visual tracking magnifier (VTM), and control groups. Reading performance was measured based on reading speed and reading error rate. The time taken to complete reading of text was measured, and reading errors were recorded. The reading performance of each group was assessed at baseline, week 2, week 6, and week 12.
Results: Reading performance was significantly different (P < 0.05) for both Level 1 and Level 2, before and after intervention only in children with dyslexia using magnifiers and VTM. Reading performance for children with dyslexia using a magnifier or a VTM increased significantly (P < 0.05) from baseline to week 2, week 6, and week 12. The improvement in reading speed was 2.5 times faster for children in the VTM group than in the other groups.
Conclusions: Simple visual aids, such as a VTM and magnifying glass, improved reading performance in children with dyslexia. The VTM intervention yielded the greatest improvement after 12 weeks of intervention. Hence, it is suggested that a VTM be used as part of a rehabilitation program for all children with dyslexia in Malaysia, particularly those in dyslexia programs in schools under the MOE Malaysia. However, future studies with longer follow-up periods are needed to confirm the sustainability of this improved reading performance after discontinuation of the intervention.