Effects of a semi-scleral contact lens on refraction and higher order aberrations

PurposeTo investigate effects of Rose K2 XL semi-scleral contact lenses (Menicon Co.) on visual acuity and higher-order aberrations in eyes with irregular corneas. Methods: One hundred and twelve eyes of 84 patients fitted with Rose K2 XL lenses were analysed. Participants were in 4 clinical groups: keratoconus, intra-corneal ring segments, radial keratotomy, and penetrating keratoplasty. Corrected distance visual acuity and ocular aberrations were determined before lens wear and 60 min into lens wear. The i-Trace aberrometer was used to determine aberrations at 4.5 mm pupil size.ResultsThere were 55, 22, 19 and 16 eyes in keratoconus, intra-corneal ring segments, radial keratotomy and penetrating keratoplasty groups, respectively. Before lens wear, eyes had poor corrected distance vision acuity (mean and standard deviation +0.55 ± 0.33 logMAR), high negative spherical equivalent refraction (−6.4 ± 3.7 D), high cylindrical errors (4.5 ± 2.2 D), large higher-order root-mean-squared (HO-RMS) aberration (1.5 ± 1.3 μm) and large higher-order aberration components. Cylinder was particular high for the penetrating keratoplasty group (mean 5.9 ± 2.5 D), root-mean-squared third-order coma was lowest for the radial keratotomy group (0.7 ± 1.0 μm), and fourth-order spherical aberration was highly negative for the intra-corneal ring segment group (co-efficient –0.4 ± 0.7 μm). With lens wear, the values changed considerably. Corrected distance visual acuity improved by 0.51 ± 0.31 logMAR, cylinder decreased by 3.6 ± 2.1 D, HO-RMS aberration reduced by 1.1 ± 1.2 μm, and higher-order aberration components decreased considerably. Magnitudes of group changes reflected the magnitudes before lens wear.ConclusionsRose K2 XL semi-scleral contact lenses were effective in improving vision and reducing ocular aberrations for eyes with irregular corneas.     

Rehabilitation of vision disabling corneal opacities: Is there hope without corneal transplant?

ObjectiveTo evaluate the efficacy of contact lenses in visual rehabilitation of a series of patients with corneal scars/opacities.MethodRetrospective review of case records of 158 patients (n = 162 eyes) with poor vision subsequent to corneal scar/opacity, who underwent contact lens fitting, was done. Primary outcome assessed was quantum of additional improvement in vision with rigid gas permeable (RGP) or soft lenses over spectacles. Success was defined as visual improvement of ≥2 lines over that of spectacles and/or improvement of vision to ≥20/60 (LogMAR 0.48).ResultsRigid gas permeable lenses were fitted in 137 eyes and soft contact lenses in 25 eyes. Lenses were successful in improving visual acuity by two or more lines over that of spectacles in 70% eyes (113 of 162 eyes), of which RGP lens accounted for 85% (96 of 113 eyes). Alternative outcome of success was defined as attainment of reasonable functional vision of >20/60 (LogMAR 0.48). This could be achieved in 65% cases (105 of 162 eyes) of which 83% (88 eyes) were with use of RGP lenses. Almost one-fourth (23.4%) patients were children less than 15 years old. Soft contact lenses were attempted in 25 instances, where RGP lens could not be fitted and were successful in 17 (68%) of these. All these 17 patients were aphakes.ConclusionsRehabilitation of corneas with visually disabling corneal opacities is possible with usage of appropriate contact lenses even in young children.     

Kerasoft IC compared to Rose-K in the management of corneal ectasias

PurposeTo determine the efficacy of the KeraSoft^® IC (KIC) (Ultravision International Limited, Bedfordshire, UK), a silicone hydrogel contact lens, for the optical management of non-surgical corneal ectasias and to compare it with the Rose-K 2 RGP contact lens.MethodsIn a retrospective study ninety-four eyes fitted with KIC (group A) were compared with seventy-seven eyes fitted with Rose-K^® RGP lenses as a control group. Ocular diagnoses, corneal curvature by topography, refraction, best spectacle-corrected visual acuity (BSCVA), and age at time of fitting were noted. Outcome data included average daily wearing time, contact lens complications, visual acuity with the lens (BCLCVA), power of the lenses and length of follow-up.ResultsDifferences in either BCLCVA or wearing time could not be statistically established (p = 0.63, p = 0.15) between both groups. More biomicroscopic complications were found in the RGP group, basically corneal staining (P < 0.0001). In the KIC group, BCLCVA was statistically similar between types of ectasia (p = 0.19) as well as in mild and moderate keratoconus (p = 0.45).ConclusionsKIC is a good alternative for the optical management of irregular corneal astigmatism in non surgical corneal ectasias such as keratoconus and pellucid marginal degeneration.     

Scleral contact lenses for visual rehabilitation after penetrating keratoplasty: Long term outcomes

PurposeTo evaluate the success rate of highly gas permeable scleral contact lenses (SCL) for visual rehabilitation after penetrating keratoplasty (PK), over a period of up to 9 years.MethodsA total database of 31 consecutive patient fitted with SCL between January 2004 and December 2009 was retrospectively reviewed. Demographic data, etiology prior to lens fitting, visual outcomes, follow up time and complications were analyzed.ResultsAll eyes were fitted due to inadequate spectacle-corrected vision after successful penetrating keratoplasty or failure of other contact lens modalities. Out of 31 patients fitted, 28 (33 eyes) continue to wear SCL for periods between 0.5 and 8.8 years. The mean duration of follow-up after contact lens fitting was 5.2 ± 2.2 years. The mean age of corneal graft was 17.6 ± 11.4 years (range 4.3–42), and the mean interval between PK and initial contact lens fitting was 12.2 ± 10.7 years (range 0.7–36.0). The average steepest keratometry of our cohort was 55.0 ± 7.5 diopter (D) and the refractive astigmatism was 8.0 ± 4.4 D. The mean contact lens corrected visual acuity (BCVAcl) was 0.78 ± 0.25 (range 0.3–1.2). Twenty-three (82%) patients achieved a functional vision of 0.5 or more.During the studied period, ten (30.0%) eyes presented at least one graft rejection episode and two eyes (6%) had an episode of microbial keratitis. Corneal transplants of 20 years or more show a higher rate of refits due to ectasia recurrence.ConclusionsScleral lenses should be considered as lens of choice in eyes with complex corneal geometry, as besides visual rehabilitation, their use may delay or prevent further surgical involvement.     

Objective and subjective visual performance of multifocal contact lenses: Pilot study

PurposeThe aim of the present study was to compare the objective and subjective visual performance of three different soft multifocal contact lenses.Methods10 subjects (habitual soft contact lens wearers) between the ages of 40 and 45 years participated in the study. Three different multifocal silicone hydrogel contact lenses (Acuvue Oasys, Air Optix and Biofinity) were fit within the same visit. All the lenses were fit according to the manufacturers’ recommendation using the respective fitting guide. Visual performance tests included low and high contrast distance and near visual acuity, contrast sensitivity, range of clear vision and through-focus curve. Objective visual performance tests included measurement of open field accommodative response at different defocus levels and optical aberrations at different viewing distances.ResultsAccommodative response was not significantly different between the three types of multifocal contact lenses at each of the accommodative stimulus levels (p > 0.05). Accommodative lag increased for higher stimulus levels for all 3 types of contact lenses. Ocular aberrations were not significantly different between these 3 contact lens designs at each of the different viewing distances (p > 0.05). In addition, optical aberrations did not significantly differ between different viewing distances for any of these lenses (p > 0.05). ANOVA revealed no significant difference in high and low contrast distance visual acuity as well as near visual acuity and contrast sensitivity function between the 3 multifocal contact lenses and spectacles (p > 0.05).ConclusionsThere was no statistically significant difference in accommodative response, optical aberrations or visual performance between the 3 multifocal contact lenses in early presbyopes.     

Comparison of conventional method of contact lens fitting and software based contact lens fitting with Medmont corneal topographer in eyes with corneal scar

PurposeTo compare conventional method of contact lens fitting with software based contact lens fitting using Medmont corneal topographer in eyes with nebular and macular corneal scars.MethodsFifteen participants who were diagnosed with nebular and macular scars were fitted with rigid gas permeable lenses using conventional method of contact lens fitting. During the lens dispensing visit, participants underwent Medmont corneal topography. Agreement between the two methods of contact lens fitting was studied.ResultsParameters of contact lenses which were concluded using conventional method was compared to that of software based fitting. Mean difference in base curve of contact lens between the two methods was 0.094 mm ± 0.147 mm (95% CI: +0.383 to −0.194). Mean difference in diameter of contact lens between the two methods was 0.16 mm ± 0.172 mm (95% CI: +0.497 to −0.177). Contact lens parameters that were achieved using two different methods of fitting showed good correlation. Correlation coefficients, as comparison of two methods in base curve and diameter were 0.96 (P < 0.05) and 0.94 (P < 0.05), respectively.ConclusionSoftware based contact lens fitting would be useful for contact lens practitioners to predict initial base curve of contact lens in corneal scars.     

Fluid filled scleral contact lens in pediatric patients: challenges and outcome

PurposeTo study the indications and the challenges while fitting scleral contact lens (ScCL) filled with fluid prior to lens insertion in pediatric patients.MethodsWe retrospectively reviewed charts of patients of 16 years or less who received ScCL (PROSE – Prosthetic Replacement of the Ocular Surface Ecosystem, Boston Foundation for Sight, Needham Heights, MA, USA) that were filled with fluid (Normal saline) before lens insertion during July 2006 to April 2010. The main goal of ScCL fitting was to improve vision in patients having keratoconus (KC) and improve the ocular microenvironment in ocular surface disease (OSD). Visual acuity before and after lens wear was noted.ResultsFluid-filled ScCL were dispensed to 15 patients (20 eyes). The indications for ScCL fitting were KC (n = 3 eyes), Stevens Johnson syndrome (SJS, n = 13 eyes), radiation keratopathy (n = 1 eye), combined KC and SJS (n = 1 eye) and KC and vernal keratoconjunctivitis (VKC, n = 2 eyes). Mean age of the patients was 12.85 years. The average daily lens wear was 9 h. The vision improved by 2 lines or more in 85% and dropped by 2 lines or more in 45% eyes after 4 h of lens wear due to tear debris collection. None of the patients had any complications. Patients were self sufficient inserting and removing ScCL. Two patients had broken lenses during the follow-up.ConclusionsScCL are useful for pediatric patients who have OSD, irregular astigmatism or the two coexisting; KC combined with VKC or SJS, helping to maintain the health of the ocular surface and improves vision in these patients.     

Soft contact lens fitting after intrastromal corneal ring segment implantation to treat keratoconus

PurposeTo assess the feasibility of fitting a lathed soft toric contact lens (STCL) after the implant of intrastromal corneal ring segments (ICRSs) to treat keratoconus.MethodsSix months after ICRS implantation, 47 eyes of 47 patients (18–45 years) were fitted with a STCL. In each eye, we determined refractive error, uncorrected (UDVA) and corrected distance visual acuity (CDVA), and keratometry and asphericity measures. The outcome of STCL fitting was defined according to CDVA as successful (≤0.2 logMAR) or unsuccessful (>0.2 logMAR). Patients in the unsuccessful group were refitted with a piggy-back (PB) system. The above variables and the change in CDVA observed after STCL and PB lens fitting from spectacle CDVA were compared in the two groups.ResultsSTCL fitting was successful in 75%, 66.66% and 0% of the ICRS implanted eyes with stages I–III keratoconus, respectively. Spectacle-CDVA was 1.5 lines better and mean corneal power was 3.62D lower in the successful STCL group. In this group, the difference in cylinder axis between spectacles and STCL was 24.25° lower. PB refitting achieved a PB-CDVA ≤0.2 logMAR in all cases. A similar difference in the CDVA change achieved by contact lenses versus spectacles was observed in the successful STCL and PB refitted groups.ConclusionSTCL fitting is a feasible option in a large proportion of patients implanted with ICRS. When these lenses are unsatisfactory, a PB system is a good alternative.     

The effect of tinted soft contact lens wear on functional visual acuity and higher-order aberrations

PurposeTo investigate the differences of functional visual acuity (FVA) and high order aberrations (HOAs) in relation to tinted and clear hydrogel soft contact lens (SCL) wear.MethodsA prospective comparative study was performed in 16 eyes of 16 healthy volunteers. Dynamic visual acuity (using a FVA measurement system) and higher-order aberrations (using a wavefront sensor) were compared in subjects wearing two types of soft contact lenses: 1-day Acuvue^® (Vistakon, Jacksonville, FL) clear and the 1-day Acuvue^® Define^TM (Vistakon, Jacksonville, FL) tinted lens. The blink rates were recorded during FVA testing. The correlation between the difference of HOAs and differences in FVA values was analyzed.ResultsThe mean LogMAR FVA scores with clear and tinted SCLs were 0.07 ± 0.13 and 0.14 ± 0.17 (P < 0.05). The mean blink frequencies with clear and tinted SCL wear were 18.4 ± 8.3 and 25.3 ± 4.7 blinks/min (P < 0.05). Both 3rd-order aberrations and total HOAs showed statistically significant differences between the two types of soft contact lenses for 6 mm pupil measurements (P < 0.05). A significant positive linear correlation was observed between ΔHOAs and ΔLogMAR FVA for 6 mm pupil measurements (R = 0.53, P = 0.04).ConclusionsTinted contact lens wear appears to induce a reduction in optical quality. Functional visual acuity measurement is a useful procedure to study the changes of visual performance and quality in tinted contact lens wear.     

Scleral contact lens management of bilateral exposure and neurotrophic keratopathy

We report an interesting case of therapeutic scleral lens management of bilateral exposure and neurotrophic keratopathy resulting from bilateral cranial nerve (CN) palsies including V, VI and VII, which caused lagophthalmos and anaesthetic corneas. Subsequent development of severe exposure keratitis with vascularisation and keratinisation of the inferior cornea was previously treated with intensive ocular lubrication, botulinum toxin injections to the upper eyelid levator muscle, temporary tarsorrhophies, bilateral amniotic membrane grafts, punctal plugs, lid taping, gold eyelid weights and soft bandage contact lenses. Corneal integrity was re-established but visual acuity remained significantly compromised by corneal vascularisation, scarring and keratin deposits. Visions on presentation to the contact lens department were R 1.90 log MAR, L 1.86 log MAR. Therapeutic, high Dk, non-fenestrated, saline filled, scleral lenses were fitted. Daily wear of these lenses have protected and hydrated the cornea, enabling corneal surface recovery whilst retaining visual and social function. The visual acuities 6 months post-scleral fitting with lenses in situ are R 0.90 log MAR and L log MAR 0.70.     

Bitoric rigid gas permeable contact lenses in the optical management of penetrating keratoplasty

PurposeThe purpose of this study was to evaluate the complexity and effectiveness of fitting bitoric rigid gas permeable contact lenses (RGPCLs), compared to spherical RGPCLS, when used in the correction of high amounts of post-penetrating keratoplasty astigmatism.MethodsRecords of post-penetrating keratoplasty (PKP) patients being managed with bitoric RGPCLs were compared to controls (post-PKP patients managed with spherical RGPCLs). Factors that were analyzed included the number of diagnostic RGPCLs used to assess the initial fit, the number of RGPCLs ordered to finalize the fit and the number of total doctor visits to finalize the fit.ResultsFourteen eyes of 14 patients satisfied the study criteria. The average amount of total astigmatism in this study group was 10.0 D ± 5.0 compared to the control group which was 3.3 D ± 2.6. The number of diagnostic RGPCLs used for the study group was 1.2 ± 0.4 compared to 1.0 ± 0.0 for the control group. The mean number of contact lenses ordered to complete the fitting for the study group was 1.9 ± 0.7 compared to the control which was 2.1 ± 0.8. The study group presented for an average of 6.3 ± 1.6 visits whereas the control group presented for 4.9 ± 1.1 visits. Contact lens corrected acuity for the study group was 0.101 ± 0.11 (20/25) compared to the control group 0.08 ± 0.12 (20/24).ConclusionsThe complexity of fitting bitoric RGPCLs was found to be similar to fitting spherical RGPCLs on post-PKP eyes and the visual outcomes were not different.     

Peripheral myopization and visual performance with experimental rigid gas permeable and soft contact lens design

PurposeTo evaluate the performance of two experimental contact lenses (CL) designed to induce relative peripheral myopic defocus in myopic eyes.MethodsTen right eyes of 10 subjects were fitted with three different CL: a soft experimental lens (ExpSCL), a rigid gas permeable experimental lens (ExpRGP) and a standard RGP lens made of the same material (StdRGP). Central and peripheral refraction was measured using a Grand Seiko open-field autorefractometer across the central 60° of the horizontal visual field. Ocular aberrations were measured with a Hartman-Shack aberrometer, and monocular contrast sensitivity function (CSF) was measured with a VCTS6500 without and with the three contact lenses.ResultsBoth experimental lenses were able to increase significantly the relative peripheral myopic defocus up to −0.50 D in the nasal field and −1.00 D in the temporal field (p < 0.05). The ExpRGP induced a significantly higher myopic defocus in the temporal field compared to the ExpSCL. ExpSCL induced significantly lower levels of Spherical-like HOA than ExpRGP for the 5 mm pupil size (p < 0.05). Both experimental lenses kept CSF within normal limits without any statistically significant change from baseline (p > 0.05).ConclusionsRGP lens design seems to be more effective to induce a significant myopic change in the relative peripheral refractive error. Both lenses preserve a good visual performance. The worsened optical quality observed in ExpRGP was due to an increased coma-like and spherical-like HOA. However, no impact on the visual quality as measured by CSF was observed.     

An acute clinical comparison of corneal staining and comfort associated with contact lens care solutions

PurposeThis study compared the biocompatibility and comfort of 4 lens care solutions currently marketed in France.MethodsThis was a randomized, interventional, double-masked, single-center crossover study assessing balafilcon A silicone hydrogel contact lenses, bilaterally, straight from the blister pack solution (control) and pre-soaked in the following lens care solutions: Regard^® (containing sodium chlorite), ReNu^® (containing a PHMB [polyhexamethylene biguanide] derivative), CyClean™ and MeniCare™ Soft (both containing PHMB). Subjects were randomized to the order of test solution use. For each of the 5 solutions tested, subjects attended a baseline/lens dispensing visit and an intervention visit 2 h later. At both visits, evaluation included slit-lamp examination, corrected-distance visual acuity, corneal staining, and subject-assessed photophobia, ocular comfort, and ocular redness.ResultsThirty subjects were enrolled and 28 were evaluable. Corneal staining severity was significantly worse than baseline after 2 h of wearing lenses soaked in CyClean, MeniCare, or ReNu (P ≤ 0.001). The MeniCare group alone demonstrated a significant improvement in ocular comfort after 2 h of lens wear (P = 0.02). No group demonstrated significant changes in ocular redness or photophobia. Corrected-distance visual acuity was similar between baseline and intervention visits for each test solution. No adverse events were reported during the study.ConclusionsSilicone hydrogel contact lenses presoaked in lens solutions containing PHMB or a PHMB derivative produced an increase in corneal staining after 2 h of lens wear. The higher levels of corneal staining in the 2 solutions did not correlate with increased discomfort within this 2-h timeframe.     

Compatibility of phospholipid liposomal spray with silicone hydrogel contact lens wear

Purpose

To assess the effects of two weeks of regular phospholipid liposomal spray application on lipid layer grade, tear film stability, subjective comfort, visual acuity, and lipid deposition in silicone hydrogel contact lens wearers.

Efficacy of two silicone-hydrogel contact lenses for bandage use after photorefractive keratectomy

PurposeTo evaluate the efficacy of two silicone hydrogel (SiH) contact lenses, approved for continuous wear for one week, following photorefractive keratectomy (PRK).MethodsForty seven myopic patients (94 eyes) undergone bilateral PRK were enrolled in this prospective, double-masked, comparative study. One eye of each patient was fitted with a Lotrafilcon B lens (Ciba Vision, Duluth, US; 30-day recommended replacement) whereas the fellow eye was fitted with an Asmofilcon A lens (Menicon, Nagoya, Japan; 14-day recommended replacement). Epithelial defect size was assessed using slit lamp biomicroscopy on the day of surgery and at days 1–4 post-operatively. Uncorrected and best-corrected visual acuity and retinal straylight (C-Quant, Oculus Optigerate, Germany) were evaluated pre-operatively and one month post-operatively.ResultsAverage epithelial defect size for Asmofilcon A and Lotrafilcon B was 25.5 ± 11.0 mm² vs. 27.1 ± 9.9 mm² at day 1 (p = 0.007) and 6.3 ± 7.0 mm² vs. 9.2 ± 9.5 mm² at day 2 (p = 0.012) post-operatively. Re-epithelialization at day 3 was completed in 87.2% of the eyes fitted with Asmofilcon A lenses, compared to 74.5% with Lotrafilcon B lenses (p = 0.012). At the 3rd post-operative day 29.8% of re-epithelialized eyes showed irregular suture with Lotrafilcon B, compared to 12.8% eyes with Asmofilcon A lenses (p < 0.001). Finally, no statistically significant differences were found post-operatively between the two lenses retinal straylight (p = 0.98) and best-corrected visual acuity (p = 0.68).ConclusionsSiH lenses can be used as an effective bandage after PRK due to the limited time requested for achieving complete corneal re-epithelialization. Faster and smoother epithelial healing is provided with Asmofilcon A over Lotrafilcon B lenses.     

Which soft contact lens power is better for piggyback fitting in keratoconus?

PurposeTo evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus.MethodsNineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of −3.00, −1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated.ResultsNegative- and plano-powered soft lenses flattened (p < 0.05 in all cases), whereas positive-powered lenses did not induce any significant changes (p > 0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (p < 0.05 in both cases) and increased with +3.00 D lenses (p = 0.03) in comparison to the naked eye. No statistically significant differences were found in MFE with any soft lens power in comparison to the naked eye (p > 0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p < 0.05 in all cases). No statistically differences were found in HOA RMS and spherical-like aberration (both p > 0.05). Statistically differences were found in coma-like and secondary astigmatism (both p < 0.05).ConclusionNegative-powered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting.     

Clinical performance of an orthokeratology lens fitted with the aid of a computer software in Chinese children

PurposeTo report the clinical performance of the orthokeratology (ortho-k) lens fitted with computer assisted system after 1-month of lens wear, in a group of children undergoing ortho-k treatment in a 2-year randomized myopic control study.MethodChildren aged 6–11 years old were fitted with the ortho-k lenses using computerized fitting. The initial myopia was 4.00–0.50 D and the initial refractive astigmatism was within 1.25 D. Lens performance, in terms of centration, myopic reduction, vision, ocular health status and lens binding incidence, was evaluated at one night, one week and one month after lens wear. Only data from the right eye was presented.ResultsThe initial spherical equivalent refraction (SER) for the 51 subjects was ?2.29 ± 0.81 D. The first fit success rate was 90%. The reduction of SER after one night and one week aftercare visit were 57% and 81%, respectively. At the one month visit, the mean reduction in SER was 89% with unaided logMAR visual acuity of 0.03 ± 0.11. Mild central corneal staining was found in 9–20% of the subjects at the aftercare visits. The incidences of lens binding at one night, one week and one month aftercare visits were 17%, 39% and 30%, respectively.ConclusionsComputer assisted system for Menicon Z Night lens fitting gave a high first fit success rate. Menicon Z Night lens was effective in myopic reduction and provided stable vision after one week of lens wear. Ocular health of the subjects after lens wear was generally unremarkable.     

Efficacy of spherical aberration correction based on contact lens power

PurposeTo investigate the efficacy of spherical aberration (SA) correction with aspheric contact lenses (aspheric lenses) based on lens power, and compare the results with those of spherical contact lenses (spherical lenses).MethodsOcular higher-order aberrations were measured with a wavefront sensor, in 11 myopic subjects wearing an aspheric lens (Medalist Fresh fit (PUREVISION 2 HD); Bausch + Lomb) or a spherical lens (ACUVUE Oasys; Johnson & Johnson). Six different lens powers (−7.00 diopters (D), −5.00 D, −3.00 D, −1.00 D, +1.00 D, +3.00 D) were used for all subjects. The amount of SA correction from the contact lens at each power was calculated as the difference between SA with the contact lens on-eye and SA of the eye alone.ResultsFor the spherical lenses, SA correction was close to 0.00 μm for the +1.00 D lens, became more positive as the labeled lens power increased and became more negative as the labeled lens power decreased. For the aspheric lenses, SA correction was consistent, from −0.15 to −0.05 μm, for all lens powers except for the −1.00 D lens. SA correction for the spherical and aspheric lenses was significantly different at −7.00 D (p = 0.040), −3.00 D (p = 0.015), −1.00 D (p < 0.001), +1.00 D (p = 0.006), and +3.00 D (p < 0.001) powers.ConclusionAn aspheric lens is capable of correcting SA at different lens powers, and has SA correction in the range of −0.15 to −0.05 μm over a 6 mm aperture.     

Corneo-scleral contact lens in a piggyback system for keratoconus: A case report

Purpose

We describe a case of fitting a corneo-scleral contact lens with a multi-aspheric geometry design (MAGD CScL) on top of a daily silicone hydrogel lens (piggyback system) for keratoconus management.