The Effect of Illumination on Positive Fusional Vergence.

Background: Positive fusional vergence (PFV) is vital in maintaining fusion in critical and continuous near tasks such as reading or performing digital screen tasks. This study investigated how PFV changed under various lighting conditions. Methods: This cross-sectional study recruited 34 participants aged between 21 and 25 years, with best corrected visual acuity (BCVA) 0.0 logMAR and insignificant refractive error. Three different illuminations-low illumination (50 lux), medium lighting (100 lux), and high illumination (150 lux)-were used to examine the ocular parameters PFV (blur, break, and recovery points), contrast sensitivity and pupil diameter. Results: Pupil diameter changed significantly in different room illuminations (p = 0.00). There was no significant difference in contrast sensitivity across the three levels of room illumination (p = 0.368). Mean PFV (SD) (blur) was 14.5 (2.5) in 50 lux, 10.2 (2.2) in 100 lux, and 8.2 (2.1) in 150 lux. Under 50, 100 and 150 lux, respectively, the mean PFV (SD) (break) values were 16.7 (2.4), 13.4 (1.8), and 10.8 (2.2), and the mean PFV (SD) (recovery) values were 13.3 (2.1), 10.7 (2.1), and 7.5 (2.7). With increased illumination levels, PFV blur, break, and recovery values were significantly lower (p < 0.001). Conclusions: PFV values were significantly higher in lower illumination. Clinicians should be aware that room illumination affected the PFV values measured.

Accommodative spasm and its different treatment approaches: A systematic review.

This article is about the accommodation spasm. The primary rule for near vision is ciliary muscle constriction, synchronised convergence of both eyes, and pupil constriction. Any weaknesses in these components could result in an accommodative spasm. Variable retinoscopic reflex, unstable refractive error, and lead of accommodation in near retinoscopy are common causes of spasm. We conducted a thorough literature search in the PubMed and Google Scholar databases for published journals prior to June 2022, with no data limitations. This review contains twenty-eight case reports, six cohort studies, four book references, four review articles, and two comparative studies after applying the inclusion and exclusion criteria. The majority of studies looked at accommodative spasm, near reflex spasm, and pseudomyopia. The most common causes of accommodative spasm are excessive close work, emotional distress, head injury, and strabismus. Despite side effects or an insufficient regimen, cycloplegic drops are effective in diagnosing accommodation spasm. The modified optical fogging technique is also effective and may be an option for treating accommodative spasm symptoms. Bifocals for near work, manifest refraction, base-in prisms, and vision therapy are some of the other management options. As a result, it requires a comprehensive clinical treatment strategy. This review aims to investigate the various aetiology and treatments responsible for accommodative spasm and proposes widely implementing the modified optical fogging method and vision therapy in clinics as comprehensive management to reduce the future upward trend of accommodative spasm.