Journal of Ophthalmic and Vision Research

Published date: Jul 21 2025

Journal Title: Journal of Ophthalmic and Vision Research

Issue title: ‎Volume 20 - 2025

Pages: 1 - 10

DOI: 10.18502/jovr.v20.13887

Vivek Suganthan Ramasubramanianviveksuganthan@gmail.comDepartment of Optometry, Faculty of Medical and Health Sciences, SRM Medical College Hospital and Research Centre, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu

Aiswaryah Radhakrishnanaiswaryr@srmist.edu.inDepartment of Optometry, Faculty of Medical and Health Sciences, SRM Medical College Hospital and Research Centre, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu

Purpose: Human vision is subnormal in an aquatic environment, and studies have used different methods to measure visual functions with water-induced blur (WIB). In this study, we compared vernier acuity measured using three different WIB simulation methods.
Methods: Sixty young adults (20 in each group) with best-corrected visual acuity of ≥6/6 participated in the study. Three different methods, one for each study group, were used to simulate WIB in order to measure the vernier acuity. The methods comprised M1: a glass tank filled with water containing a wave motor to produce waves, M2: a sprinkler with uncontrolled water splash against the glass, and M3: a sprinkler with controlled water splash against the glass. For each of the three methods, vernier acuity was measured binocularly (three trials of 50 presentations each) both at baseline (without simulated WIB) in the absence of WIB and under simulated WIB. This was conducted using FrACT presented on the Display++ monitor at a distance of 2 meters from the participant. The vernier target consisted of two vertical lines (1 x 15 arcmin) with a vertical separation of 0.5 arcmin.
Results: The mean baseline vernier acuity (arcsec) was found to be similar (F [2, 57] = 0.20, P = 0.82) among all three groups (M1: 13.28 ± 5.84, M2: 14.44 ± 6.34, M3: 14.05 ± 3.28). Vernier acuity with simulated WIB was least degraded with M1 (19.84 ± 8.40) and more degraded with M2 (288.74 ± 56.61), followed by M3 (49.14 ± 20.13). One-way ANOVA revealed a significant difference among the three methods (F [2, 57] = 354.72, P < 0.001).
Conclusion: Our results suggest that the impact of simulated WIB on vernier acuity is not comparable due to differences in the strength of blur and the varied spatial and temporal properties of different simulated WIB methods. This emphasizes the need to develop a blur metric specific to WIB to objectively quantify its effect on different visual functions.

Keywords: Hyperacuity, Underwater Blur, Underwater Vision, Vernier Acuity, Vision

1. Barlow HB. Dark and light adaptation: Psychophysics. Visual psychophysics. Springer; 1972. pp. 1–28.

2. Mankowska A, Aziz K, Cufflin MP, Whitaker D, Mallen EA. Effect of blur adaptation on human parafoveal vision. Invest Ophthalmol Vis Sci 2012;53:1145–1150.

3. Sawides L, de Gracia P, Dorronsoro C, Webster MA, Marcos S. Vision is adapted to the natural level of blur present in the retinal image. PLoS One 2011;6:e27031.

4. Webster MA, Georgeson MA, Webster SM. Neural adjustments to image blur. Nat Neurosci 2002;5:839–840.

5. Pasture C, Montagnini A, Perrinet LU. Humans adapt their anticipatory eye movements to the volatility of visual motion properties. PLOS Comput Biol 2020;16(4).

6. Tsao DY, Livingstone MS. Mechanisms of face perception. Annu Rev Neurosci 2008;31:411–437.

7. Gislén A, Warrant EJ, Dacke M, Kröger RH. Visual training improves underwater vision in children. Vision Res 2006;46:3443–3450.

8. Gislén A, Dacke M, Kröger RH, Abrahamsson M, Nilsson DE, Warrant EJ. Superior underwater vision in a human population of sea gypsies. Curr Biol 2003;13:833–836.

9. Sawides L, de Gracia P, Dorronsoro C, Webster M, Marcos S. Adapting to blur produced by ocular high-order aberrations. J Vis 2011;11:1–21.

10. Sabesan R, Yoon G. Visual performance after correcting higher order aberrations in keratoconic eyes. J Vis 2009;9:6.1–10.

11. Sabesan R, Yoon G. Neural compensation for longterm asymmetric optical blur to improve visual performance in keratoconic eyes. Invest Ophthalmol Vis Sci 2010;51:3835–3839.

12. Sawides L, Marcos S, Ravikumar S, Thibos L, Bradley A, Webster M. Adaptation to astigmatic blur. J Vis 2010;10:22.

13. Vinas M, Sawides L, de Gracia P, Marcos S. Perceptual adaptation to the correction of natural astigmatism. PLoS One 2012;7:e46361.

14. Gislén A, Gislén L. On the optical theory of underwater vision in humans. J Opt Soc Am A Opt Image Sci Vis 2004;21:2061–2064.

15. Mass AM, Supin AY. Adaptive features of aquatic mammals’ eye. Anat Rec (Hoboken) 2007;290:701–715.

16. Artal P, Guirao A. Contributions of the cornea and the lens to the aberrations of the human eye. Opt Lett 1998;23:1713–1715.

17. Weiffen M, Möller B, Mauck B, Dehnhardt G. Effect of water turbidity on the visual acuity of harbor seals (Phoca vitulina). Vision Res 2006;46:1777–1783.

18. Seemakurthy K, Rajagopalan AN. Deskewing of underwater images. IEEE Trans Image Process 2015;24:1046–1059.

19. Atchison DA, Valentine EL, Gibson G, Thomas HR, Oh S, Pyo YA, et al. Vision in water. J Vis 2013;13:4.

20. Radhakrishnan A, Ramasubramanian VS. Fixational Performance and Visual Function changes underwater in normal eyes. Invest Ophthalmol Vis Sci 2021;62:ARVO E-Abstract 2822.

21. Cramer JL. Comparative analysis of unaided emmetropic and unaided noncorrected myopic underwater visual acuity. Res Q Am Assoc Health Phys Educ 1975;46:100–109.

22. Westheimer G. The spatial sense of the eye. Proctor lecture. Invest Ophthalmol Vis Sci 1979;18:893–912.

23. Levi DM, Klein SA, Aitsebaomo AP. Vernier acuity, crowding and cortical magnification. Vision Res 1985;25:963–977.

24. Wehrhahn C, Westheimer G. How vernier acuity depends on contrast. Exp Brain Res 1990;80:618–620.

25. Lakshminarayanan V, Enoch JM. Vernier acuity and aging. Int Ophthalmol 1995;19:109–115.

26. Levi DM, Polat U, Hu YS. Improvement in Vernier acuity in adults with amblyopia. Practice makes better. Invest Ophthalmol Vis Sci 1997;38:1493–1510.

27. Otto J, Michelson G. Repetitive tests of visual function improved visual acuity in young subjects. Br J Ophthalmol 2014;98:383–386.

28. Enoch JM, Williams RA, Esock EA, Fensick M. Hyperacuity: A promising means of evaluating vision through cataract. Prog Retinal Res 1985;4:67–88.

29. Bach M. The Freiburg Visual Acuity Test-variability unchanged by post-hoc re-analysis. Graefes Arch Clin Exp Ophthalmol 2007;245:965–971.

30. Sara U, Akter M, Uddin MS. Image quality assessment through FSIM, SSIM, MSE and PSNR—A comparative study. JCC 2019;07:8–18.

31. Berry RN, Riggs LA, Richards W. The relation of vernier and depth discrimination to width of test rod. J Exp Psychol 1950;40:520–522.

32. Stigmar G. Observations on vernier and stereo acuity with special reference to their relationship. Acta Ophthalmol (Copenh). 1970;48(5):979–98.

33. Stigmar G. Blurred visual stimuli. II. The effect of blurred visual stimuli on vernier and stereo acuity. Acta Ophthalmol (Copenh) 1971;49:364–379.

34. Krauskopf J, Farell B. Vernier acuity: Effects of chromatic content, blur and contrast. Vision Res 1991;31:735–749.

35. Whitaker D, Elliott DB, MacVeigh D. Variations in hyperacuity performance with age. Ophthalmic Physiol Opt 1992;12:29–32.

36. Komori Y, Kono I, Saito M, Sakata I. Effects of swimming on vision. Tairyoku Kagaku 1999;48:403–412.

37. Donate A, Ribeiro E. Improved reconstruction of images distorted by water waves. In: Braz J, Ranchordas A, Araújo H, Jorge J, editors. Advances in computer graphics and computer vision. Berlin, Heidelberg: Springer Berlin Heidelberg; 2007. pp. 264–77.

38. Bailey IL. Mobility and visual performance under dim illumination. In: Night Vision: Current Research and Future Directions, Symposium Proceedings. National Academies Press; 1987. 220 p.