To determine the repeatability of retinal nerve fiber layer (RNFL) measurement from 2 spectral domain optical coherence tomography (OCT) instruments and assess the level of agreement. A secondary objective was to assess if pupillary dilatation affected the repeatability of RNFL measurement. Prospective, observational study. Fifty normal participants were recruited after being screened for exclusion criteria, which included preexisting glaucoma and significant cataract. Peripapillary RNFL thickness was measured from either eye of the 50 participants using both the Cirrus and Spectralis OCTs. Three scans were performed consecutively for each instrument and the process was repeated after pupillary dilatation. Test-retest variability, coefficient of variation, and intraclass correlation coefficient (ICC) for repeatability of RNFL measurement. ICC and Bland-Altman plots for agreement between both devices. Test-retest variability for the Cirrus and Spectralis OCTs were 4.89 μm and 4.95 μm, respectively. RNFL measurements were less repeatable in the 4 quadrants, ranging from 5.02 to 15.00 μm. The temporal quadrant was the most repeatable quadrant for the Cirrus OCT with a variability of 7.81 μm, whereas the nasal quadrant was the most repeatable for Spectralis OCT with 5.02 μm. Test-retest variability was poorer for the Cirrus OCT in the nasal, inferior, and superior quadrants. Pupillary dilatation increased repeatability of RNFL measurement for Cirrus OCT, particularly in the superior quadrant, whereas not affecting measurements from Spectralis OCT. ICC values for agreement between both instruments were good. For average RNFL as well as RNFL in the superior, inferior, and temporal quadrants, ICC ranged from 0.859 to 0.908. The nasal quadrant had a lower ICC of 0.663. Bland-Altman plots showed that the Spectralis OCT provided the thicker RNFL measurement in general, except in the nasal quadrant when RNFL was thin. The repeatability of RNFL thickness measurement in normal participants was excellent for both the Cirrus and Spectralis OCTs. Agreement of RNFL measurement between both the devices was generally good, with the exception of the nasal quadrant in which a linear relationship exists. Pupillary dilatation improved the repeatability of RNFL measurement for Cirrus while having minimal influence on Spectralis OCT. More studies will be required to ascertain the relationships of RNFL measurement between the different spectral domain OCT instruments in normal and glaucomatous patients.

Purpose: A percentage tissue altered (PTA) score of ≥40% has been advocated as an independent indicator of post-operative ectasia risk following laser in-situ keratomileusis (LASIK). This study was performed to test the hypothesis that refractive procedures, such as laser-assisted sub-epithelial keratectomy (LASEK) or small incision lenticule extraction (SMILE), may alter the range of PTA, within which refractive corneal surgery can be safely performed. Setting: Refractive department, tertiary ophthalmic hospital. Design: Retrospective observational study. Methods: Review of case notes was performed for patients who presented for refractive surgeries, other than LASIK. To determine the risk of corneal ectasia for each patient prior to refractive surgery, we estimated what each patient’s PTA would have been if they had undergone LASIK. The Randleman Ectasia Risk Score System (ERSS) was also calculated. Results: 114 eyes (66 patients) were included. 94 eyes underwent SMILE. 20 eyes underwent LASEK. A significant proportion of eyes had PTA ≥40% – SMILE eyes: up to 31.9%, LASEK eyes: up to 60.0% (at presumed LASIK flap of 120 μm). The maximum calculated PTA was up to 47.9% in the SMILE group and up to 51.5% in the LASEK group. Using ERSS, 12.8–16% of SMILE eyes and 15.0–80.0% of LASEK eyes would have been considered to have moderate-to-high ectasia risk. No post-surgical ectasia was observed at 3 years. Conclusion: SMILE and LASEK alter the range of PTA, within which corneal refractive surgery may be performed with a lower risk of developing post-operative corneal ectasia; a safe PTA threshold needs to be determined for these procedures before recommendations for clinical practice can be made.

Isotretinoin is a highly effective treatment for moderate-to-severe acne vulgaris but is associated with a broad spectrum of ophthalmic adverse effects. While dry eye disease secondary to meibomian gland dysfunction is the most common ocular complication, less familiar manifestations include nyctalopia, corneal abnormalities, retinal changes, idiopathic intracranial hypertension, and optic neuritis. Current evidence suggests that isotretinoin induces structural and functional changes in the meibomian glands, resulting in tear film instability and evaporative dry eye disease. Although many of these changes appear reversible following treatment cessation, some patients may experience persistent symptoms. This review was conducted as a structured narrative review of the ophthalmic adverse effects associated with systemic isotretinoin use. A literature search was performed using PubMed and Embase for articles published from inception to 1 June 2026. Nyctalopia is a well-established adverse effect attributable to rod photoreceptor dysfunction and may have important implications for occupations requiring optimal night vision. Corneal remodelling and ocular surface dysfunction are particularly relevant in contact lens wearers and patients considering refractive and corneal surgery, for instance corneal transplants. Rare but potentially sight-threatening neuro-ophthalmic complications have also been reported. Clinicians prescribing isotretinoin should routinely enquire about visual symptoms and maintain a low threshold for ophthalmic referral. Early recognition and collaborative management between dermatologists, general practitioners, and eye care practitioners are essential to minimise visual morbidity, promote ocular comfort and optimise patient outcomes. This review aimed to provide an updated, clinically focused synthesis of the ophthalmic adverse effects of isotretinoin, emphasising pathophysiological mechanisms, clinical presentation, evidence supporting reversibility, and practical recommendations for ophthalmologists, dermatologists, and primary care clinicians.