Rigid Gas Permeable Contact Lenses for Keratoconus Review
Introduction
National System for Rare Disorders defines keratoconus as an eye (ocular) disorder characterized by progressive thinning and changes in the shape of the cornea.ane It is a noninflammatory corneal ectasia that induces irregular astigmatism, myopia, and protrusion, leading to impairment in the quality of vision.2 Spectacles are useful in the early stages of keratoconus when the astigmatism is mild. With advanced keratoconus, glasses play a very limited role and contact lenses become necessary for improving the vision, sometimes avoiding surgery that is more invasive.3 Corneal transplant is a therapeutic option for avant-garde disease, when spectacle correction is insufficient, contact lens vesture is intolerable and visual acuity is at an unacceptable level.four Diverse options for contact lenses (CLs) are available, which include toric soft, corneal gas-permeable (RGPCL), piggyback, hybrid (HCL), and scleral lenses.4 To fit CLs is a challenge in patients with keratoconus. The pick of CL frequently depends on the anatomical fit on the cornea/sclera, the comfort provided by the CL, the toll of the lens, and the visual operation.5
Regarding visual operation, the monocular loftier-dissimilarity distance visual acuity is the virtually commonly used measurement of vision in clinical do but it is not representative plenty of the full complexity of the patient's routine visual experience. It can be a poor predictor of some aspects of vision function.6–12 Quality of vision is a subjective entity based on an individual'south unique and multifactorial perception of their vision, influenced by both visual and psychological factors.13 It is difficult to define the quality of vision by a unmarried parameter. The assessment can include contrast sensitivity, disability glare, intraocular devious low-cal, and aberrometry.fourteen For case, contrast sensitivity has been found to correlate well with various aspects of visual power, including orientation and mobility,viii,eleven,15 reading speed,16 and driving.15
For keratoconus, the improvement of monocular loftier-contrast visual vigil with CLs is well-established, just fewer reports are available on the improvement of quality of vision with different CL modalities, all relative to spectacles, and do non necessarily compare different CL designs.5,17–22 Our study aimed to analyze the visual functioning in keratoconus patients already fitted with different CL materials and designs.
Materials and Methods
Study Pattern
A cohort study including keratoconus patients fitted with CLs in the Ophthalmology Section of Centro Hospitalar Universitário practise Porto (CHUPorto), between June 2019 and March 2021. This study was conducted following the tenets of the Declaration of Helsinki (1964). The authors ensured that all patients' anonymity was advisedly protected. Informed consent was signed for all procedures. Approval was obtained from the "Departamento de Ensino, Formação eastward Investigação" (DEFI).
Participants
The inclusion criteria were as follows: adult patients; diagnosis of keratoconus (according to the criteria developed by the Global Consensus on Keratoconus and Ectatic Diseases); and well-fitted CL wearers (comfortable lens for as long as necessary on a instance-past-case basis; daily use; none or minimal lens awareness; clear and stable vision; no or occasional need for rewetting drop).23 Patients who missed the complete clinical evaluation (complete functional and structural analysis detailed in parameters section) were included in "loss to follow-upwardly" and they were excluded from effect analysis. The apply of different types of CLs in the past was non an exclusion criterion.
Parameters
The following variables were analyzed: demographic characteristics; functional and structural outcomes.
a) The demographic characteristics:
-historic period and gender;
-previous ocular surgeries;
-CL specifications (current CL fitted): type, time of wear, and spherical equivalent.
b) The functional analysis:
-current monocular high-contrast distance best-corrected visual acuity with contact lens (BCVA-CL) and with glasses (BCVA-Southward) correction evaluated by Snellen Chart;
-contrast sensitivity (CS) in the various spatial frequencies under photopic (PCS) and mesopic weather condition (MCS) evaluated by Metrovision-MonPack3® (grating luminance's of lxxx cd/m2 in the photopic exam and 0.08 cd/m2 in the low mesopic examination): hateful PCS and MCS were considered the value on the 2–5cpd interval;
-analysis of calorie-free scattering in the retina evaluated by Hard disk Analyzer®: the objective besprinkle alphabetize (OSI), the modular transfer function (MTF), the predicted visual acuities (decimal) within the 100% contrast level (PVA100), the 20% contrast level (PVA20) and the ix% dissimilarity level (PVA9);
-the affect of the tear film on dynamic optical quality evaluated by Hard disk Analyzer®: vision break-up time (VBUT), OSI dynamically measured 40 times in a 20-2d flow as a surrogate of tear film stability (dOSI). Minimum OSI (minOSI), maximum OSI (maxOSI), and OSI amplitude (ampOSI) were considered in that period.
c) The structural analysis:
-corneal tomographic parameters measured by Oculus Pentcam® Hour: maximum, minimum and mean G, corneal thickness at the thinnest betoken (TP), Belin-Ambrósio deviation alphabetize (BAD-D), root mean square higher-gild abnormality (RMS-HOA), and root mean foursquare total (RMS-TOTAL);
-retinal tomographic parameters measured by Heildelberg Spectralis® spectral-domain optical coherence tomography: primal macular thickness (CMT), subfoveal choroidal thickness (SCT), and optic disc nerve fiber layer thickness (OD-NFL).
All evaluations considered and detailed in a higher place were performed in two different timings:
- without CL and previously to CL plumbing fixtures: functional analysis (BCVA-S) and structural analysis (corneal tomographic parameters)
- with CL fitted and in this order: functional analysis (BCVA-CL, CS, analysis of light scattering in the retina and the bear on of the tear film on dynamic optical quality) and structural analysis (retinal tomographic parameters).
The Oct was performed while patients wearing CLs due to logistic reasons (so that patients did non need to have off CL in the 2d evaluation time). There are some contradictory reports about the influence of CL during analysis with optical coherence tomography.24–26 This structural evaluation was performed to control other causes of poor quality of vision, which can present in these patients.
Statistical Analysis
Statistical analysis was performed using the SPSS programme (SPSS Statistics, version 22.0 for Windows, SPSS Inc., IBM, Somers, NY). The normality of the variables was evaluated past the Kolmogorov–Smirnov examination. The comparison betwixt independent continuous variables was performed using the Isle of mann–Whitney test and T-Pupil test. The Fisher exact test was used for nominal scaled data. Spearman'south bivariate correlation test was applied to study correlations. P values less than 0.05 were considered statistically significant.
Results
Demographic Data
Sixty-8 patients were initially included. 9 patients vest to "loss to follow-upwardly" due to non-attendance for complete clinical evaluation and they were not included in the analysis: 3 patients were emigrant, 3 patients had given upwards wearing CL and were waiting to corneal transplant, ii patients were recovering from other health problems and i was very satisfied and did not desire such an early review. Therefore, we analysed 96 optics of 59 patients, 64.4% (38/59) male person and 35.six% (21/59) female, anile xix to lxx years, with a mean historic period of 42.9 ± 12.8 years (y) at the fourth dimension of consummate visual functioning evaluation. Concerning ocular history, 29.17% (28/96) of cases had undergone previous ocular surgery: 15.6% (xv/96) intrastromal corneal band implant, 11.5% (11/96) penetrating keratoplasty, and ii.1% (2/96) deep anterior lamellar keratoplasty. In that location was no case of corneal cantankerous-linking in our sample.
Rigid gas permeable contact lenses (RGPCL), hybrid contact lenses (HCL), and silicone hydrogel/hydrogel contact lenses (HGCL) were fitted in 67, 17, and 12 eyes respectively. The specific CLs fitted were:
- RGPCL grouping: Menicon EX/Z/S9/B4PM/KRC (31/67), Rose K2 (15/67), Hanita BXO Thousand/Wolhk KE (15/67), Ocellus k2 (three/67), Fluorolens fifty Menicon David Thomas (2/67) and OCP (1/67);
- HCL group: SynergEyes A/KC (15/17) and Duette (2/17);
- HGCL group: Biofinity toric (6/12), Soflex k67 (2/12), Frequency Xcel toric (two/12), Purevision toric (one/12), and AirOptix for astigmatism (1/12).
The age (p = 0.382), gender (p = 0.875), time of CL wear (p = 0.382) and spherical equivalent (p = 0.078) were similar among groups (Table 1).
 | Table ane Demographic Data |
Visual Quality Analysis
All parameters analysed are detailed in Table 2. Overall, the mean BCVA-CL was improve than BCVA-S (p < 0.001) and it was like amidst CL groups (p = 0.618) (Effigy 1A). Hateful PCS was better with RGPCL (p = 0.020) and HCL (p = 0.004) than with HGCL. In that location were no statistically meaning differences (p = 0.071) betwixt PCS with RGPCL and HCL. Mean MCS was similar among groups (p = 0.121) (Figure 1B). Concerning light scattering analysis, hateful OSI (p = 0.134), PVA100 (p = 0.131), PVA20 (p = 0.120), PVA9 (p = 0.054) and MTF (p = 0.105) were similar among groups. Hateful PVA by groups is represented in Figure 1C. Dynamic optical quality showed statistical differences: mean dOSI (p = 0.024), maxOSI (p = 0.040) and minOSI (p = 0.037) were better in RGPCL group and worse in HGCL group. The hateful ampOSI was similar (p = 0.165) among groups (Figure 1D). OSI was meaning correlated with historic period (r = 0.429, p < 0.001), fourth dimension of CL vesture (r = 0.249, p = 0.017), spherical equivalent (r = −0.392, p < 0.001) and SCT (r = −0.470, p < 0.001), but non with other structural parameters (Table 3). Patients with previous ocular surgery had similar visual performance to others in all functional parameters (p > 0.05).
 | Tabular array two Functional and Structural Outcomes |
 | Table three OSI Correlations |
 | Figure 1 The variation of some variables co-ordinate to unlike patients groups: rigid gas permeable contact lens (RGPCL), hybrid contact lens (HCL) and silicone hydrogel/hydrogel contact lens (HGCL). (A) Mean all-time-corrected visual acuity with spectacles (BCVA-S) (p = 0.199) and with contact lens (BCVA-CL) (p = 0.618). (B) Mean dissimilarity sensitivity under photopic weather (PCS) (p = 0.006) and mesopic conditions (MCS) (p = 0.121). (C) Mean predicted visual acuities within the 100% contrast level (PVA100) (p = 0.131), inside the 20% contrast level (PVA20) (p = 0.120) and within the 9% contrast level (PVA9) (p = 0.054). (D) Mean dynamically measured OSI: minimum (MinOSI) (p = 0.037), mean (p = 0.024) and maximum (MaxOSI) (p = 0.040). (E) Hateful k minimum (mink) (p = 0.034), mean (p = 0.020) and maximum (maxK) (p = 0.294). (F) Mean fundamental macular thickness (CMT) (p = 0.617), subfoveal choroidal thickness (SCT) (p = 0.822) and optic disc nerve cobweb layer thickness (OD-NFL) (p = 0.818). |
Structural Analysis
Concerning corneal tomographic parameters, mean minK (p = 0.034), mean Thousand (p = 0.020), TP (p = 0.011) and BAD-D (p = 0.013) were worse in RGPCL and better in HGCL group. Mean Chiliad values in each group are represented in Figure 1E. RMS-HOA (p = 0.372) and RMS-Full (p = 0.601) were similar among groups.
Regarding posterior pole structural analysis, the mean CMT (p = 0.617), SCT (p = 0.822), and OD-NFL (p = 0.818) were like among groups (Effigy 1F).
Examples
In Figures 2, 3 clinical cases are represented with similar historic period, gender, and spherical equivalent, fitted with three different groups of CLs. In all these cases, in that location was an increased BCVA with CL, but the other visual quality parameters differed among groups. Along with the cases (Figure 2A–C), OSI, VBUT, and CS worsened, despite amend corneal tomographic parameters.
 | Figure 2 Three clinical examples. They were chosen considering they have a like historic period, gender, and spherical equivalent, fitted with 3 different contact lenses. (A) Patient fitted with a rigid gas permeable contact lens (RGPCL). (B) Patient fitted with a hybrid contact lens (HCL). (C) Patient fitted with a silicone hydrogel/hydrogel contact lens (HGCL). In all these cases, it was an increased best-corrected visual acuity with contact lens, but the other visual quality parameters differed among groups. Along with the cases (A–C), objective scatter alphabetize, vision break-upward time, and dissimilarity sensitivity worsened, despite better corneal tomographic parameters. |
Discussion
The results of the present report advise a meaning visual quality variation for different types of CL fitted in patients with keratoconus, despite the similar BCVA-CL. Although this is a real-life study, our CLs groups are significantly homogeneous every bit to age, gender, time of CL wear, and spherical equivalent, which allows comparisons amongst them.
Regarding dissimilarity sensitivity, HGCL showed worse performance in photopic weather, and all CLs were associated with a decreased contrast sensitivity in mesopic conditions. This is a characteristic of keratoconus patients even without CLs27 and may impact on patients' daily activities and professional performance, like the ability to drive, despite good BCVA. Although analysis of light scattering in the retina revealed no differences, the dynamic optical quality analysis highlighted the touch on that tear movie tin take on visual quality. As to this parameter RGPCL showed a meaning advantage in visual performance despite more advanced keratoconus and HGCL had the worst results. Tear lens is the main reason that RGPCL or HCL provides ameliorate visual quality by decreasing higher-society aberrations arising from anterior corneal surface irregularity. Although the function of tear exchange is less discussed, it should be clinically paid attention to in those cases with decreased quality of vision compared to spectacle wearing. Tear commutation beneath CLs is lower during soft lenses article of clothing when compared with rigid lenses wear, resulting in more accumulation of tear film debris and metabolic by-products between the cornea and CLs.28 The correlations found betwixt OSI and historic period29 and spherical equivalent30 are non new. The correlation found between OSI and the time of CL wear may be explained past the fact that patients with more time of CL wearable are older. The correlation between OSI and SCT can be explained by the fact that patients with lower SCT are myopic. However, there was no correlation between corneal tomographic parameters and OSI.31 Probably, the fitted CL can contribute to decreasing aberrations and decreasing lite handful on the retina.
Apropos corneal structural analysis, we concluded that the three groups were non homogenous as regards the caste of disease. Nevertheless, patients fitted with RGPCL had more advanced degrees of keratoconus and were simultaneously the grouping with the best visual performance. Lastly, the posterior pole tomographic parameters analysis allowed u.s. to exclude differences in retinal and optic nervus parameters that might influence our visual quality analysis interfering with the results.
Since not all types of contact lens are suitable to all patients with keratoconus, prescription can be a large challenge. Therefore, one of the aims of this work is to highlight that in CL fitting process, professionals must take into business relationship not just visual acuity but also the quality of vision, as this may touch on daily-life activities.
2 of the strengths of this study are the inclusion of real-life patients and the multimodal assessment of visual quality, allowing us to sympathize virtually of the limitations of these patients. We did not desire to exclude patients with previous corneal treatments because these patients are an increasingly frequent reality in our medical appointments. The assessment was performed by merely 1 doctor (IB) and 2 technicians (DA and DJ).
The major limitation of this study is that it consists in comparing heterogeneous groups regarding stages of the illness. However, information technology is virtually incommunicable to find patients well fitted with these 3 types of CLs for all stages of the disease. Additionally, this report is non randomized and has no control grouping. The randomization is not plausible because this written report is an evaluation of patients already well adjusted to CLs and not called for this study. A control grouping, peculiarly in cases of more advanced affliction, is not suitable, as visual acuity is bad without correction and correction with glasses is not possible and surgical options are not to exist considered when achieving proficient visual performance with contact lenses. Comparing the visual functioning of the different CLs in the same patient would be ideal, but it would not be feasible in patients with keratoconus. In nigh cases, fitted lenses are the merely suitable option, so it would not be possible to assess the quality of vision with poorly fitted CLs, which exercise not stabilize, might crusade corneal trauma, or do not allow acceptable visual vigil, etc. These formats are without doubt very interesting in theoretical terms, just they do non piece of work with CLs fitted for utilize in everyday life, especially in more advanced keratoconus. Occasionally, especially in less developed keratoconus, CLs could be put on but for the cess of vision and quality of vision even if they were non well-fitted enough to be prescribed. Likewise, CLs often seem well-fitted, but the patient sees poorly with them. For this reason, it is non appropriate to test the quality of vision, because they will not exist prescribed either. In our opinion, the ideal methodology would be to compare the quality of vision with dissimilar types of CLs, well adapted to the same eye. Withal, they would always take to be adapted under the same conditions, allowing plenty time between evaluations, to regularize the shape of the cornea subsequently CL removal, a situation that we consider completely utopian. Another limitation of this written report is that it did not address the issue of quality of life in the CL choice process. Sometimes, patients can adopt lower visual vigil and quality of vision to choose an pick that provides them a meliorate quality of life or lower costs. The quality of vision assessed in this report was also not correlated with daily performance. Lastly, this report did not include all CLs options available in the international market for keratoconus (eg, ClearKone) and included some CLs non specifically designed for keratoconus (eg, Duette), which means that the results must be interpreted with caution and cannot exist generalized.
Overall, our study demonstrates that contact lenses should not be forgotten equally a valid option in keratoconus patients baring in heed that in the CLs fitting process not only visual acuity simply too the quality of vision must be taken into account, which is often forgotten, despite the fact that both aspects may bear upon daily-life activities.
Acknowledgments
The authors want to admit all the support granted by the Caput of the Ophthalmology Section of Centro Hospitalar due east Universitário do Porto, Prof. Dr. Pedro Menéres. The manuscript has been presented in public every bit an oral advice at two events: World Ophthalmology Congress 2020 Virtual and CIRP 2021 (Reunion of Cornea, cataract and ocular surface specialists), June, Santa Eulália, Portugal.
Funding
This research received no specific grant from whatever funding agency in the public, commercial, or not-for-turn a profit sectors.
Disclosure
The authors declare that they accept no conflicts of involvement in this work.
References
one. Keratoconus [Internet]. NORD (National Arrangement for Rare Disorders). [cited June 7, 2021]. Available from: https://rarediseases.org/rare-diseases/keratoconus/.
two. Rabinowitz YS. Keratoconus. Surv Ophthalmol. 1998;42(4):297–319. doi:10.1016/S0039-6257(97)00119-seven
3. Rathi VM, Mandathara PS, Dumpati S. Contact lens in keratoconus. Indian J Ophthalmol. 2013;61(8):410–415. doi:ten.4103/0301-4738.116066
4. Mandathara PS, Stapleton FJ, Willcox MDP. Outcome of keratoconus management: review of the past 20 years' contemporary treatment modalities. Eye Contact Lens. 2017;43(3):141–154. doi:10.1097/ICL.0000000000000270
5. Kumar P, Bandela PK, Bharadwaj SR. Do visual operation and optical quality vary across unlike contact lens correction modalities in keratoconus? Contact Lens Anterior Middle. 2020;43(vi):568–576. doi:ten.1016/j.clae.2020.03.009
6. Hess R, Woo Yard. Vision through cataracts. Invest Ophthalmol Vis Sci. 1978;17(v):428–435.
7. Paulsson LE, Sjöstrand J. Dissimilarity sensitivity in the presence of a glare calorie-free. Theoretical concepts and preliminary clinical studies. Invest Ophthalmol Vis Sci. 1980;19(four):401–406.
8. Marron JA, Bailey IL. Visual factors and orientation-mobility operation. Am J Optom Physiol Opt. 1982;59(v):413–426. doi:10.1097/00006324-198205000-00009
9. Owsley C, Sloane ME. Contrast sensitivity, vigil, and the perception of 'real-world' targets. Br J Ophthalmol. 1987;71(x):791–796. doi:ten.1136/bjo.71.10.791
10. Elliott DB, Hurst MA. Simple clinical techniques to evaluate visual function in patients with early cataract. Optom Vis Sci. 1990;67(eleven):822–825. doi:x.1097/00006324-199011000-00006
11. Elliott DB, Hurst MA, Weatherill J. Comparing clinical tests of visual function in cataract with the patient's perceived visual disability. Eye (Lond). 1990;four(Pt 5):712–717. doi:ten.1038/eye.1990.100
12. Mangione CM, Phillips RS, Lawrence MG, Seddon JM, Orav EJ, Goldman Fifty. Improved visual office and attenuation of declines in health-related quality of life afterward cataract extraction. Curvation Ophthalmol. 1994;112(11):1419–1425. doi:10.1001/archopht.1994.01090230033017
xiii. McAlinden C, Pesudovs K, Moore JE. The development of an instrument to measure quality of vision: the Quality of Vision (QoV) questionnaire. Invest Ophthalmol Vis Sci. 2010;51(11):5537–5545. doi:x.1167/iovs.10-5341
14. Parede TRR, Torricelli AAM, Mukai A, Vieira Netto Chiliad, Bechara SJ. Quality of vision in refractive and cataract surgery, indirect measurers: review commodity. Arq Bras Oftalmol. 2013;76:386–390. doi:10.1590/S0004-27492013000600016
xv. Rubin GS, Roche KB, Prasada-Rao P, Fried LP. Visual impairment and disability in older adults. Optom Vis Sci. 1994;71(12):750–760. doi:ten.1097/00006324-199412000-00005
16. Leat SJ, Woodhouse JM. Reading performance with low vision aids: relationship with dissimilarity sensitivity. Ophthalmic Physiol Opt. 1993;13(1):ix–sixteen. doi:x.1111/j.1475-1313.1993.tb00420.x
17. Negishi One thousand, Kumanomido T, Utsumi Y, Tsubota K. Upshot of higher-order aberrations on visual role in keratoconic eyes with a rigid gas permeable contact lens. Am J Ophthalmol. 2007;144(six):924–929. doi:10.1016/j.ajo.2007.08.004
eighteen. Montalt JC, Porcar Due east, España-Gregori E, Peris-MartÃnez C. Visual quality with corneo-scleral contact lenses for keratoconus direction. Cont Lens Anterior Middle. 2018;41(4):351–356. doi:10.1016/j.clae.2018.01.002
19. Metlapally S, Bharadwaj SR, Roorda Aet al. Binocular cantankerous-correlation analyses of the effects of high-lodge aberrations on the stereoacuity of eyes with keratoconus. J Vis. 2019;19(6):12. doi:ten.1167/19.half-dozen.12
20. Nilagiri VK, Metlapally S, Kalaiselvan P, Schor CM, Bharadwaj SR. LogMAR and stereoacuity in keratoconus corrected with spectacles and rigid gas-permeable contact lenses. Optom Vis Sci. 2018;95(4):391–398. doi:10.1097/OPX.0000000000001205
21. Sherafat H, White JE, Pullum KW, Adams GG, Sloper JJ. Anomalies of binocular function in patients with longstanding asymmetric keratoconus. Br J Ophthalmol. 2001;85(nine):1057–1060. doi:10.1136/bjo.85.9.1057
22. Gumus K, Gire A, Pflugfelder SC. The touch of the Boston ocular surface prosthesis on wavefront higher-order aberrations. Am J Ophthalmol. 2011;151(4):682–690.e2. doi:10.1016/j.ajo.2010.x.027
23. Gomes JAP, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359–369. doi:10.1097/ICO.0000000000000408
24. Aviram T, Beeri I, Berkow D, Zayit-Soudry S, Blumenthal EZ, Shapira Y. The upshot of contact lens wear on retinal spectral domain optical coherence tomography. Clin Exp Optom. 2020;103(6):792–797. doi:10.1111/cxo.13064
25. Berkenstock MK, Parikh RA, Collins Physician, et al. Use of contact lenses to optimize October scans of the optic nerve in glaucoma suspects or patients with glaucoma with high myopia. Ophthalmol Glaucoma. 2020;3(3):196–201. doi:10.1016/j.ogla.2020.01.002
26. Salchow DJ, Hwang AM, Li F-Y, Dziura J. Outcome of contact lens power on optical coherence tomography of the retinal nervus fiber layer. Invest Ophthalmol Vis Sci. 2011;52(3):1650–1654. doi:10.1167/iovs.10-6118
27. Zarei-Ghanavati S, Khakshour H, Vejdani Grand, Ghooshkhanei H, Vejdani A. Evaluation of changes in visual vigil, contrast sensitivity and aberrations in patients with keratoconus after corneal collagen cross-linking. J Ophthalmic Vis Res. 2017;12(3):260–264. doi:10.4103/jovr.jovr_30_16
28. Muntz A, Subbaraman LN, Sorbara L, Jones L. Tear commutation and contact lenses: a review. J Optom. 2015;eight(one):ii–eleven. doi:ten.1016/j.optom.2014.12.001
29. Artal P, Benito A, Pérez GM, et al. An objective besprinkle index based on double-laissez passer retinal images of a point source to allocate cataracts. PLoS One. 2011;half dozen(ii):e16823. doi:ten.1371/journal.pone.0016823
30. Miao H, Tian M, He L, Zhao J, Mo 10, Zhou X. Objective optical quality and intraocular scattering in myopic adults. Invest Ophthalmol Vis Sci. 2014;55(9):5582–5587. doi:10.1167/iovs.14-14362
31. Leonard AP, Gardner SD, Rocha KM, Zeldin ER, Tremblay DM, Waring GO. Double-pass retina signal imaging for the evaluation of optical light scatter, retinal image quality, and staging of keratoconus. J Refract Surg. 2016;32(11):760–765. doi:ten.3928/1081597X-20160728-02
Source: https://www.dovepress.com/keratoconus-and-visual-performance-with-different-contact-lenses-peer-reviewed-fulltext-article-OPTH
0 Response to "Rigid Gas Permeable Contact Lenses for Keratoconus Review"
Postar um comentário