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- 1. JOURNAL CLUB Arjun Sapkota FinalYear, B.Optometry Maharajgunj medical Campus KATHMANDU
- 2. Visual functions in tintedsoft contact lens
- 3. Effect of thepigment-free optical zone diameter of decorative tinted soft contact lenses on visual function Ji Won Jung,1,2 Sang Myung Kim,1 Sun Hyup Han,1 Eung Kweon Kim,1,3 Kyoung Yul Seo,1 Tae-im Kim
- 4. • 1 Departmentof Ophthalmology, The Institute of Vision Research, Yonsei University College of Medicine,Seoul, South Korea • 2 Department of Ophthalmology and Inha Vision Science Laboratory, Inha University School of Medicine, Incheon, South Korea • 3 Corneal Dystrophy Research Institute, Severance Biomedical Science Institute, and Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea
- 5. Introduction • Contact lensesare thin and curved disk that are rested directly on the surface of the eye for vision correction • Apart from vision correction, these lenses are also used as a sign of fashion • Now-a-days everyone is interested to wear contact lenses due to the advances in optical technology, comfortability, easier to wear and its effectiveness
- 6. • Coloured contactlenses are the most stylish update of existing version that allows the instant transformation of the entire appearance of the wearer by changing the colour of the pupil • High quality coloured contact lenses are manufactured by renowned contact lenses brands like Bausch and Lomb, Freshlook and Freshkon
- 7. Parameters • Total Diameter-14.00 mm to 14.50 mm • Optic Zone diameter 6.00 mm Base curve- median(8.60)mm
- 8. • The globalmarket for contact lenses - 4.5% per annum.1 • Approx. 1/3rd of all contact lens wearers use decorative tinted soft contact lenses.1 2 • A decorative tinted soft contact lens contains a central pigment-free optical zone and a peripheral pigment-tinted area 1 The 2010 Study of the Intern’l Market for Contact Lenses conducted by Multi-sponsor Surveys International LLC. http://multisponsorinternational.com (accessed 9 Aug 2014) 2 Rah MJ, Schafer J, Zhang L, et al. A meta-analysis of studies on cosmetically tinted soft contact lenses. Clin Ophthalmol 2013;7:2037–42
- 9. Has acosmetic effect of making the corneal diameter appear larger and accentuating the iris color Demographical data- that the population using such cosmetic contact lenses primarily consists of young females.3 Mostly use these lenses mainly for cosmetic purposes 3 .Singh S, Satani D, Patel A, et al. Colored cosmetic contact lenses: an unsafe trend in the younger generation. Cornea 2012;31:777–9.
- 10. • Most ofthe lenses are obtained from an over-the-counter source, an unlicensed optical shop.3 4 • Especially, the surface pigments on poorly manufactured decorative tinted lenses can increase surface roughness, which might promote bacterial adhesion and infection.5 3. Singh S, Satani D, Patel A, et al. Colored cosmetic contact lenses: an unsafe trend In the younger generation. Cornea 2012;31:777–9. 4. Steinemann TL, Pinninti U, Szczotka LB, et al. Ocular complications associated with the use of cosmetic contact lenses from unlicensed vendors. Eye Contact Lens 2003;29:196–200. 5.Chan KY, Cho P, Boost M. Microbial adherence to cosmetic contact lenses. Cont Lens Anterior Eye 2014;37:267–72.
- 11. • Lenses werepreviously reported to have adverse effects on visual performance, including visual field constriction, night vision disturbances and decline in contrast sensitivity.6 7 • Tinted lens wearers sometimes complain about blurred vision even despite preserved visual acuity 6 Spraul CW, Roth HJ, Gäckle H, et al. Influence of special-effect contact lenses (crazy lenses) on visual function. CLAO J 1998;24:29–32. 7 Ozkagnici A, Zengin N, Kamiş O, et al. Do daily wear opaquely tinted hydrogel soft contact lenses affect contrast sensitivity function at one meter? Eye Contact Lens 2003;29:48–9.
- 12. • Several methodsto evaluate visual quality using aberrometer and functional visual acuity (FVA) instrument have been introduced and studies of tinted lenses have been reported.8–11 • Market research- that many tinted contact lenses with varying sizes of the central pigment-free optical zone and users preferred lenses with smaller central pigment-free zone and larger peripheral pigment-tinted zone for dramatic effect on iris color or shape 8 Hiraoka T, Ishii Y, Okamoto F, et al. Influence of cosmetically tinted soft contact lenses on higher-order wavefront aberrations and visual performance. Graefes Arch Clin Exp Ophthalmol 2009;247:225–33. 9 Takabayashi N, Hiraoka T, Kiuchi T, et al. Influence of decorative lenses on higher-order wavefront aberrations. Jpn J Ophthalmol 2013;57:335–40. 10 Watanabe K, Kaido M, Ishida R, et al. The effect of tinted soft contact lens wear on functional visual acuity and higher-order aberrations. Contact Lens Anterior Eye 2014;37:203–8. 11 Ortiz C, Jiménez R. Optical quality and vision with iris-coloring soft contact lenses. Optom Vis Sci 2014;91:564–9.
- 13. • To evaluatethe effects of the different pigment free optical zone diameters on visual function • To investigate the mechanism underlying the decreased visual quality after wearing the tinted lenses Objective of the study
- 14. MATERIALS AND METHODS •Prospective study • 30 eyes from 30 normal subjects • Best-corrected visual acuity (BCVA) of ≥20/20 • No any history of ocular disease, previous ocular surgery or systemic disorders that may affect the VA
- 15. • Prescreening slit-lampexamination was performed on all eyes - to confirm absence of ocular pathologies • Informed consent for participation in the study was obtained after the study protocol had been fully explained
- 16. • Tinted SCLSof 3 different central pigment-free optical zone diameter of 4, 5 and 6 mm were manufactured and used in this study • Peripheral area of the lenses consisted of dark-coloured pigment-tinted zone based on a modification of daily- wear tinted lens (eyelike Callamatch II, Koryo Eyetech Co, Seoul, Korea)
- 17. • The totaldiameter (TD )- 14.0 mm Base Curve - 8.6 mm • The lens material- modified polymacon with a water content of 40% • The characteristics of the clear lens (eyeLIKe Shine, Koryo Eyetech Co) were the same as those of the tinted soft contact lens
- 18. • Slit-lamp examinationwas performed on all subjects • To confirm the contact lenses fitted comfortably in the centre both vertically and horizontally and repositioned within 0.5–1.0 mm during a single blink before measurement in all subjects
- 19. • BCVA, ocularaberrations, modulation transfer function (MTF), the Strehl ratio & CS were evaluated after wearing the clear & decorative tinted soft contact lenses with various diameters of pigment-free optical zone • The lenses were worn in a random order with at least 1 hr of rest between wearing lenses, which allowed for full equilibrium on the eye
- 20. • Each lenswas worn for at least 30 mins prior to any measurements • Ocular aberrations measured by iTrace (Tracey Technologies, Houston, Texas, USA; software V.4.1.0) through a natural pupil without using dilating drugs at a fixed entrance scan size of 4.0 mm • Measurements were repeated at least 3 times and the best scan was chosen for the final analysis
- 21. • The datawere considered valid after confirming that there were < 9 rejected points in the measurement • The iTrace automatically displayed ocular aberration measurements in root mean square (RMS) values
- 22. • MTF andStrehl ratio were obtained from the ray-tracing aberrometer for a 4 mm pupil size • Strehl ratio is the ratio of peak focal intensity in aberration versus an ideal point spread function,12 and it provides general information about the eye’s optical quality • A value of 1 corresponds to a perfect zero-aberration optical system
- 23. • Contrast sensitivitymeasured by Optec 6500 test system (Stereo Optical Co, Chicago, Illinois, USA) at five spatial frequencies (1.5, 3, 6, 12 and 18 cycles/degree (cpd) under photopic (luminance value of 85candelas/square metre (cd/m2)) and mesopic conditions (target luminance value of 3 cd/m2) with or without glare • Intense illumination of 12 white light emitting diodes around the field (10 lx for photopic; 1 lx for mesopic) was used as a source of glare
- 24. • Ocular aberrationand contrast sensitivity scores were compared using repeated-measures analysis of variance (ANOVA) incorporating, where necessary, a Greenhouse– Geisser correction for non-sphericity • If significant differences were observed with the ANOVA test, paired t test was performed to determine significant differences among the four conditions
- 25. • Because ofmultiple comparisons, an adjusted p value was used after Bonferroni correction, and significance was defined as a probability value of <0.05 • The blocked pupil covered by the tinted area of lens was measured by subtracting the pigment-free optical zone diameter from pupil size
- 26. • The pupilsize was measured using the iTrace in mesopic condition • Correlation between the higher-order aberrations (HOAs) and the blocked pupil was analysed using linear regression analysis and Pearson’s correlation
- 27. Result • A totalof 30 eyes of 30 subjects (11 men and 19 women) were included • The mean age of the subjects in this study was 28.8 ±3.5 years (range, 21–37 years) • The mean BCVA was 0.00 logMAR and mean spherical equivalent was −1.2±1.7 D (range, −6.0 to 0.0 dioptres)
- 28. • The meanmesopic pupil size, measured using the iTrace, was 6.4±0.5 mm • BCVA was 0.00±0.00 logMAR for the clear lens, 0.01±0.02, 0.01±0.03 and 0.04±0.04 logMAR for the tinted contact lenses with 6, 5 and 4 mm pigment-free optical zone, respectively (p<0.001, repeated-measures ANOVA)
- 29. • Using thepaired t test, no significance for difference in BCVA between the clear lens and 6 or 5 mm tinted lenses was observed • However, after wearing the lens with 4 mm optical zone, the BCVA decreased significantly (p<0.001)
- 30. Effects of thepigment-free optical zone diameter of tinted soft contact lenses on ocular optical quality
- 31. • With decreasein pigment-free optical zone diameter, ocular aberrations except trefoil aberration increased significantly (all p<0.050) • The mean RMS values of the total HOAs were 0.238±0.112 for the clear lens, 0.298±0.123 mm for 6 mm, 0.535±0.197 mm for 5 mm and 0.600±0.245 mm for 4 mm pigment-free optical zone lens (p<0.001, repeated measures ANOVA)
- 32. • No significantdifference between clear lens and 6 mm optical zone diameter lens for all ocular aberrations • Total HOAs, coma aberration and secondary astigmatism showed significant difference between clear lens and 5 or 4 mm sized optical zone lenses (adjusted p<0.050 after Bonferroni correction, paired t test)
- 33. • Spherical aberrationand trefoil aberration showed significant difference between clear lens and 4 mm sized optical zone lens (adjusted p<0.050) • The results of the Strehl ratio revealed poorer optical quality for both 5 and 4 mm pigment-free optical zone lens, compared with clear lens (both adjusted p=0.002).
- 34. • The entireocular MTF was significantly different, corresponding to the decreased pigment-free optical zone diameter at all spatial frequencies (p<0.001, repeated- measures ANOVA)
- 36. Correlation between ocularaberrations and the blocked pupil covered by the tinted area of the lenses • Showed a strong correlation between the blocked pupil covered by the tinted area of the lens and ocular aberration including total HOAs (r=0.435, p<0.001, Pearson’s correlation coefficient), coma aberration (r=0.266, p=0.027) and secondary astigmatism (r=0.316, p=0.008) • Linear regression analysis showed that total HOAs, coma aberration and secondary astigmatism were significantly increased, consistent with the increased pupil diameter covered by the tinted section of decorative lens
- 38. Effects of thepigment-free optical zone diameter of decorative tinted soft contact lenses on contrast sensitivity • As the pigment-free optical zone diameter decreased, contrast sensitivity also decreased significantly under photopic condition without stimuli of glare at spatial frequency 12 cpd (p=0.027,repeated-measures ANOVA)
- 39. • Under mesopicconditions, contrast sensitivity significantly decreased at spatial frequency of 3 and 6 cpd with or without glare stimulation (all p<0.05, repeated measures ANOVA) • Under these conditions, only the difference between the clear lens and 5 or 4 mm sized optical zone lenses showed statistical significance (adjusted p<0.05 after Bonferroni correction, paired t test
- 41. DISCUSSION • The changesin visual functions after wearing tinted soft contact lenses with different diameters for pigment free optical zones were investigated • Compared with the clear lens with the same diopter, the tinted soft contact lens with the smallest pigment free optical zone (4 mm) showed a significant reduction in BCVA.
- 42. • Some studiesrecently demonstrated increased aberration & altered visual function after wearing tinted contact lenses, but used tinted lenses with different optical zone diameters & did not adequately address the varying effects of different diameters of the pigment-free zones.8–11 • The deteriorating effects of the tinted lens on visual function in relation to the diameter of central pigment-free optical zone were investigated • In the current study, ocular aberrations except trefoil increased significantly, corresponding to the decreased pigment-free optical zone diameter.
- 43. • Results showedthat total HOAs, coma aberration & secondary astigmatism showed a significant difference between clear lens and 4 or 5 mm optical zone lenses • Spherical aberration and trefoil showed a significant difference between clear lens and 4 mm optical zone lens. • However the difference in ocular aberrations between the clear and 6 mm tinted lens was not significant.
- 44. • Hiraoka etal8- tinted contact lenses increase ocular HOAs and worsen contrast sensitivity • Used a tinted soft lens with a central clear zone of 5.4 mm & reported the changes in ocular HOAs for a 4 mm pupil suggested several possible explanations • 1st, corneal change/unstable lens surface due to the differences of water content or physical property between clear & tinted area could have caused the ocular aberration in eyes wearing tinted lens
- 45. • The relevanceof surface roughness of the tinted area of the lenses had been reported in other studies,5 13 • 2nd, conside a proper lens movement of about 0.5–1 mm on a blink, the center of tinted lens was unlikely to coincide with the corneal center all the time; the tinted area covering the pupil might have obscured the vision • Present study-ocular aberration is more aggravated by a smaller optical zone diameter lens, which agrees with the second reason
- 46. • Takabayashi etal9 described the influence of decorative lenses on HOAs in different pupil sizes using two tinted lenses with 6.2 and 8.7 mm central clear zones • Compared with those of the clear lenses, HOAs of both tinted lens groups increased significantly • No difference in HOAs between the two tinted lenses
- 47. • Poorly fittingdecorative lenses also had larger RMS values of the total HOAs than did appropriately fitting clear lenses • Explained that the increase in HOAs including coma-like aberrations was caused by the mismatched optical centers despite the appropriate fit and minimal movement (<1 mm) on blinking
- 48. • Watanabe etal10 assessed the differences of FVA & HOAs in relation to tinted & clear soft contact lens wear • Used a tinted lens with 6.2 mm central clear zone & showed the decline of FVA and the increase of coma-like aberrations • Suggested -minute changes in lens position during natural blinks might have increased the HOAs causing a decrease in FVA, according to the pupil size
- 49. • Previously-researchers believedthat pupil size influenced the visual performance after wearing tinted lens,8–11 the results failed to reveal direct correlation between HOAs and pupil size • In this study, used the blocked pupil as the indicator & showed a positive correlation between increased ocular aberrations, including total HOAs, coma aberration, 20 astigmatism,& the blocked pupil • Because of natural displacement of the lens by blinking-a transient and partial mismatch between the centres of the lens and the cornea, causing disruption in the light transmittance
- 50. • In addition,factors such as light scattering at the border between optical and tinted areas and rugged surface of the lens likely contributed to the increase in ocular aberration • Such factors became more significant as the optical zone diameter was decreased
- 51. • Also, theresults of the Strehl ratio and entire ocular MTF revealed poorer optical quality corresponding to the decreased optical zone diameter • Small optical zones of tinted lenses could have induced ocular aberrations which compromise optical qualities significantly.12 14 • Demonstrated- CS significantly diminished under photopic and mesopic conditions as the pigment-free optical zone diameter decreased
- 52. • Reduced contrastsensitivity in response to tinted lenses was considered as the result of increased HOAs induced by the tinted contact lenses.8 • Although clear contact lenses might decrease contrast sensitivity due to residual astigmatism,15 spherical aberration,16 contact lens deposits17 and corneal oedema,18
- 53. • This studyshowed- the tinted soft contact lens exhibited more serious reduction in contrast sensitivity,A/C to the pigment-free optical zone diameter • So, the reduction in contrast sensitivity after wearing tinted lenses might have been also caused by induced HOA and altered light transmittance by the blocked pupil.
- 54. • Although thisstudy was limited by its small size, it was revealed that, as the pigment-free optical zone diameter decreased, • the tinted soft contact lens significantly increased ocular aberrations and decreased optical quality and contrast sensitivity
- 55. • Optical effectof partially covered pupil might play a role in the increased ocular aberrations after wearing tinted lenses • Based on these results, consumers using tinted contact lenses should be informed of potential side effects on visual function related to the small pigment-free optical zone of the lens
- 56. • In addition,nostatistically significant difference in aberration, corrected vision and contrast sensitivity between clear lens and 6 mm optical zone diameter lens • A minimum diameter of 6 mm pigment-free optical zone should be established and regulated as a standard for decorative tinted lenses approval
- 57. Conclusion • Decorative tintedcontact lenses significantly increases ocular aberrations and decreases optical quality & contrast sensitivity, as the pigment free optical zone diameter decreased • Finally, tinted lenses users should be informed about the possible disturbance in visual function
- 58.