Semiautomated SD-OCT Measurements of Corneal Sublayer Thickness in Normal and Post-SMILE Eyes

Purpose:To test the reliability of a novel algorithm for measuring corneal epithelial thickness (ET) and stromal thickness of normal eyes and post-small incision lenticule extraction (SMILE) corneas with spectral-domain optical coherence tomography.Methods:In this prospective observational study, a customized semiautomated software algorithm was developed and applied to measure corneal ET and stromal thickness along the horizontal corneal meridian. Measurements were performed by 2 examiners in a randomized fashion on a sample of 40 eyes with previous SMILE for treatment of myopia and a control group composed of 40 normal eyes. The intrauser repeatability and interuser reproducibility were analyzed by calculating typical indices including the coefficient of variation and intraclass correlation coefficient. Corneal sublayer thickness profiles were compared between normal and post-SMILE eyes.Results:In both groups, coefficients of variation were 3.2% or lower and intraclass correlation coefficients were 0.929 or higher indicating excellent reliability of the measurement method. Central ET was on an average 6 m greater in post-SMILE corneas (58.8 5.4 m) compared with normal eyes (52.8 +/- 4.0 m), with P < 0.01. Also, there was greater interindividual variability in ET in post-SMILE corneas and their horizontal epithelial profile seemed to show a lenticular appearance.Conclusions:Highly favorable indices of measurement reliability were achieved for this novel method of measuring corneal sublayer pachymetry not only in normal eyes but also in eyes with previous SMILE. The corneal ET profile was significantly altered in post-SMILE eyes compared with normal corneas

Differences in optic nerve head blood flow regulation in normal tension glaucoma patients and healthy controls as assessed with laser speckle flowgraphy during the water drinking test

Précis: Optic nerve head (ONH) perfusion was not significantly altered in subjects with normal tension glaucoma (NTG) nor in healthy individuals after performing the water drinking test (WDT), because of its limited effect on ocular perfusion pressure (OPP). Purpose: ONH blood flow can be maintained stable in healthy individuals because of a physiological phenomenon called autoregulation. Impairment of autoregulation has been shown especially under condition of NTG. The purpose of this study was to investigate the ONH blood flow autoregulation in patients with NTG by influencing the OPP with the WDT. Methods: The study included 9 eyes from 9 white patients with a diagnosis of NTG and 9 eyes from age-matched and sex-matched healthy individuals. In the glaucoma group, the antiglaucomatous therapy was paused 3 weeks before the investigations. Measurements of ONH blood flow were performed with laser speckle flowgraphy. After baseline measurements, individuals ingested 800 mL of water in <5 minutes. Measurements were repeated after 15, 30, and 45 minutes. Results: The water ingestion led to a significant rise in intraocular pressure (P<0.001) but also mean arterial pressure (P<0.001) in both groups. This resulted in stable OPP (P=0.051) with no significant difference between the groups (P=0.43). ONH blood flow remained stable over time in both groups (P=0.719). No significant interaction of time and group was shown for all parameters. Conclusions: Our findings show that the WDT does not significantly influence the OPP and therefore has to be considered inferior to other methods used to assess blood flow autoregulation

Comparison of deep sclerokeratodissection, a new variant of nonpenetrating glaucoma surgery, with deep sclerectomy

Purpose: The aim of this study was to evaluate the safety and efficacy of deep sclerokeratodissection (DSKD), a new nonpenetrating technique in glaucoma surgery. Materials and Methods: Retrospective comparison between patients treated with DSKS or deep sclerectomy (DS) between 2013 and 2014. In DSKD, the first and only flap is dissected directly into clear cornea with unroofing Schlemm's canal. Beside routine clinical follow-up (visual acuity, intraocular pressure [IOP] readings, slit lamp and fundus examination), postoperative ultrasound biomicroscopy (UBM) investigation and quality of life (QoL) assessment were performed. Statistically significant differences were determined by parametric or nonparametric tests, depending on normality. Results: Twelve (38.7%) DSKDs and 19 (61.3%) conventional DS' were included in this analysis. IOP decreased significantly from 21.5 ± 9.2 mmHg to 6.2 ± 5.4 mmHg on day 1, 13.4 ± 7.7 at 1 month, 12.0 ± 4.1 at 3 months, 12.5 ± 3.1 mmHg at 6 months, and 13.4 ± 4.3 mmHg at 12 months (P 0.1). There was no significant difference in intra- and post-operative complications, the morphology of the surgical site in the UBM as well as in the QoL assessment. Conclusion: The results indicate that DSKD is a safe and efficient new variant of nonpenetrating glaucoma surgery. IOP can be lowered as effectively compared to conventional DS, with a similarly low rate of complications. Further reports are necessary to confirm these results