Medical hypothesis discovery and innovation in ophthalmology

The purpose of this study was to identify which of the eye solutions is best for sodium fluorescein staining of the cornea to diagnose dry eye disease. The study included 173 eyes with suspected or known dry eye disease. The eyes were stained sequentially with sodium fluorescein and each of the following four conditions: balanced salt solution (BSS); BSS and cyclosporine 0.05% emulsion; BSS and lipids containing omega-3; and BSS, cyclosporine 0.05% emulsion, and lipids containing omega-3. Our results showed that compared to BSS alone, artificial tears with cyclosporine 0.05% emulsion and lipids containing omega-3 remain in the cornea for longer periods, thus allowing the clinician to evaluate tear break-up time and visualize corneal punctate erosions.

We aimed to compare the effect of accelerated and conventional corneal collagen cross-linking (CXL) on visual, refractive, and topographic parameters in patients with progressive keratoconus. Between December 2014 and February 2016, at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Iran, we compared 37 eyes of 21 patients treated by conventional CXL (CCXL; 3 mW/cm2 in 30 minutes) with 34 eyes of 18 patients treated by accelerated CXL (ACXL; 18 mW/cm2 in 5 minutes) based on generalizing estimation equation analysis in terms of corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), corneal endothelial cell indices, and topographic parameters before and at 3, 6 and 12 months after the operation. The mean UDVA and spherical equivalent changes were similar in the two groups, but an improvement in CDVA was only observed in the CCXL group (P = 0.003). Keratometry (minimum and maximum) was significantly decreased in the CCXL group (P = 0.043 and P = 0.008, respectively). Indices of keratoconus progression—surface asymmetry index (SAI), keratoconus prediction index (KPI), and keratoconus index (KCI)—were significantly lower in the CCXL group than in the ACXL group (P = 0.002, P < 0.001, and P < 0.001, respectively). The thinnest corneal thickness (TCT) was not significantly different between the two groups (P = 0.15). The reduction of corneal endothelial cell density was also similar between the two groups; however, polymorphism and polymegethism were significantly lower in the ACXL group than in the CCXL group. In conclusion, we showed that although ACXL at 18 mW/cm2 slowed keratoconus progression safely during a 1-year follow-up, CCXL at 3 mW/cm2 may be superior in the prevention of keratoconus progression.

Helicobacter pylori is a prevalent cause of gastrointestinal infections. Recently, several studies have shown a relationship between H. pylori infection and a variety of extradigestive manifestations. The aim of this study was to review the literature regarding the prevalence of this infection in cases of central serous chorioretinopathy (CSR). We reviewed the EMBASE, Cochrane Library, and Google Scholar search engines; hand-searched many journals; and searched the cited references in published articles for relevant studies. We assessed 81 studies for eligibility. Finally, nine articles that met the inclusion criteria were included. The relationship between H. pylori infection (as the etiologic factor) and chorioretinal involvement was assessed by the effect size with 95% confidence interval (CI). Both fixed- and random-effects models showed that the prevalence of H. pylori infection in patients with CSR was significantly higher than in the control group (2.5-fold and 2.7-fold higher, respectively; P < 0.01). The results were not significantly different between the two models. Treatment of H. pylori infection should be considered in patients with CSR. However, additional randomized controlled clinical trials are required to determine the possible role of H. pylori eradication in the prognosis and treatment of patients with CSR.

Perimetry is one of the mainstays in glaucoma diagnosis and treatment. Various strategies offer different accuracies in glaucoma testing. Our aim was to determine and compare the diagnostic sensitivity and specificity of Swedish Interactive Threshold Algorithm (SITA) Fast and Standard Full Threshold (SFT) strategies of the Humphrey Field Analyzer (HFA) in identifying patients with visual field defect in glaucoma disease. This prospective observational case series study was conducted in a university-based eye hospital. A total of 37 eyes of 20 patients with glaucoma were evaluated using the central 30-2 program and both the SITA Fast and SFT strategies. Both strategies were performed for each strategy in each session and for four times in a 2-week period. Data were analyzed using the Student’s t-test, analysis of variance, and chi-square test. The SITA Fast and SFT strategies had similar sensitivity of 93.3%. The specificity of SITA Fast and SFT strategies was 57.4% and 71.4% respectively. The mean duration of SFT tests was 14.6 minutes, and that of SITA Fast tests was 5.45 minutes (a statistically significant 62.5% reduction). In gray scale plots, visual field defect was less deep in SITA Fast than in SFT; however, more points had significant defect (p < 0.5% and p < 1%) in pattern deviation plots in SITA Fast than in SFT; these differences were not clinically significant. In conclusion, the SITA Fast strategy showed higher sensitivity for detection of glaucoma compared to the SFT strategy, yet with reduced specificity; however, the shorter test duration makes it a more acceptable choice in many clinical situations, especially for children, elderly, and those with musculoskeletal diseases.

Considering the rising number of MyoRing implantation procedures in keratoconic corneas and the refractive outcomes associated with this treatment modality, this study aimed to evaluate and compare the magnitude and axis orientation of total and corneal astigmatism between before and after MyoRing implantation in 34 eyes of 28 patients with keratoconus (KCN) (mean age: 29.41 ± 7.0 years). The inclusion criterion was a reliable diagnosis of clinical KCN based on corneal biomicroscopic and tomographic findings. The mean total astigmatism of ocular refraction decreased significantly from -4.27 ± 3.15 D (before MyoRing implantation) to -2.18 ± 1.63 D (after MyoRing implantation) (P < 0.001). The mean astigmatism in the anterior and posterior surface of the cornea decreased significantly by 1.16 D (P = 0.001) and 0.24 D (P = 0.009), respectively, after MyoRing implantation. Before MyoRing implantation, the axis orientation of total ocular astigmatism for with-the-rule, oblique, and against-the-rule astigmatism was 21%, 42%, and 37%, respectively; at 6 months after MyoRing implantation, it was 18%, 24%, and 58%, respectively. Before MyoRing implantation, the axis orientation for with-the-rule, against-the-rule, and oblique astigmatism of the anterior surface of the cornea was 59%, 24%, and 17%, respectively; at 6 months after MyoRing implantation, it was 52%, 24%, and 24%, respectively. Before MyoRing implantation, the axis orientation of with-the-rule, oblique, and against-the-rule astigmatism of the posterior surface of the cornea was 68%, 29%, and 3%, respectively; at 6 months after MyoRing implantation, it was 67%, 12%, and 12%, respectively. MyoRing implantation significantly decreased the amount of total, anterior, and posterior corneal astigmatism.

We aimed to compare the results of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling, an alternative therapeutic strategy, with those of medical treatment for chronic macular edema. We conducted a review of the literature on the microscopic, anatomical, and functional reasons for performing PPV with ILM peeling in patients with diabetic macular edema (DME). We searched the PubMed database for articles published between 2000 and 2017. We used the medical subject heading vitrectomy diabetic macular edema and the keywords diabetic macular edema, internal limiting membrane peeling, pars plana vitrectomy, diabetic retinopathy, and optical coherence tomography. Analysis of the literature revealed that cytokines, vascular endothelial growth factor, reactive oxygen species (ROS), and advanced glycation end-products (AGEs) play a unique role in DME. The vitreous cavity serves as a physiological reservoir for all inflammatory molecules. AGE receptors are localized at the footplates of Muller cells and the external limiting membrane (ELM). The footplates of Muller cells are in contact with the ILM, which suggests that they might be responsible for the structural damage (i.e., thickening) observed in the ILM of patients with DME. Therefore, PPV could allow a reduction of cytokines and pro-inflammatory molecules from the vitreous cavity. ILM peeling could eliminate not only the physical traction of a thickened structure, but also the natural reservoir of AGEs, ROS, and inflammatory molecules. PPV with ILM peeling is a surgical option that should be considered when treating patients with chronic DME.