Rigid Gas Permeable Research Articles

Efficacy and Safety Comparison among Rigid Gas Permeable Contact Lens Correction for Keratoconus

Background: Rigid gas-permeable contact lenses (RGP CL) are commonly used to manage moderate tosevere keratoconus. The range of RGP CL type currently available for the successful optical correctionof keratoconus has greatly expanded. We compared the efficacy and safety of available RGP CL basedon visual acuity (VA), keratometry, comfort score, and adverse event.Methods: Literature search on RGP CL and keratoconus retrieved 37 citations from 2010-2015. Ninearticles were selected as relevant to our purpose.Results: All studies showed improvement of VA following RGP CL wearing. Greatest improvementwas seen in Rose K CL (.5 - .36) in naïve CL patient and Twinbel bevel toric in refitting CL patient(.22). All studies reported lower mean ΔK post fitting RGP CL than pre-fitting. Greatest difference ofmean ΔK pre and post-fitting was observed in YK lens (.72). The most comfortable lens was Rose K(91.5%) followed by Soper CL (87.9%) and Twinbel bevel toric (64.4%). Punctuate corneal stainingfound in a considerable amount with YK lens patient.Conclusion: Among 5 types of RGP CL available now for keratoconus, Rose K provided greatestBCVA improvement in naïve CL patient whereas Twinbel bevel toric in refitting patient. YK lensgave greater changes in keratometry post-fitting RGP CL. The most comfortable lens for patient isRose K lens. The most common adverse event of CL wear is punctuate corneal staining in YK lenspatient.Keywords: rigid gas permeable contact lens, keratoconus

New web-based algorithm to improve rigid gas permeable contact lens fitting in keratoconus.

To calculate and validate a new web-based algorithm for selecting the back optic zone radius (BOZR) of spherical gas permeable (GP) lens in keratoconus eyes. A retrospective calculation (n=35; multiple regression analysis) and a posterior prospective validation (new sample of 50 keratoconus eyes) of a new algorithm to select the BOZR of spherical KAKC design GP lenses (Conoptica) in keratoconus were conducted. BOZR calculated with the new algorithm, manufacturer guidelines and APEX software were compared with the BOZR that was finally prescribed. Number of diagnostic lenses, ordered lenses and visits to achieve optimal fitting were recorded and compared those obtained for a control group [50 healthy eyes fitted with spherical GP (BIAS design; Conoptica)]. The new algorithm highly correlated with the final BOZR fitted (r2=0.825, p<0.001). BOZR of the first diagnostic lens using the new algorithm demonstrated lower difference with the final BOZR prescribed (-0.01±0.12mm, p=0.65; 58% difference≤0.05mm) than with the manufacturer guidelines (+0.12±0.22mm, p<0.001; 26% difference≤0.05mm) and APEX software (-0.14±0.16mm, p=0.001; 34% difference≤0.05mm). Close numbers of diagnostic lens (1.6±0.8, 1.3±0.5; p=0.02), ordered lens (1.4±0.6, 1.1±0.3; P<0.001), and visits (3.4±0.7, 3.2±0.4; p=0.08) were required to fit keratoconus and healthy eyes, respectively. This new algorithm (free access at www.calculens.com) improves spherical KAKC GP fitting in keratoconus and can reduce the practitioner and patient chair time to achieve a final acceptable fit in keratoconus. This algorithm reduces differences between keratoconus GP fitting (KAKC design) and standard GP (BIAS design) lenses fitting in healthy eyes.

Effect of Rigid Gas Permeable Contact Lenses on Nystagmus and Visual Function in Hyperopic Patients with Infantile Nystagmus Syndrome

ABSTRACTPurpose: To determine the effect of rigid gas permeable contact lenses (RGPCL) on involuntary eye movements and visual function in hyperopic patients with infantile nystagmus syndrome. Methods: This prospective interventional case series was conducted on 16 patients with infantile nystagmus and hyperopia equal or more than +0.5 D and astigmatism more than -1 D over a 2-year period. A complete ophthalmological examination including determination of best corrected visual acuity (BCVA), contrast sensitivity, and videonystagmography was performed for all patients before and after at least 3 months of RGPCL use, and the outcomes were compared. Results: Thirty-two eyes of 16 patients with mean age of 18.6±4.9 years were enrolled. Mean spherical equivalent refractive error was +1.5±2.35 (range +1 to +6.25) diopters (D); corresponding values were +2.45±2.44 D (range +0.5 to +7.5) for spherical error and +1.90±0.83 D (range +1 to +4) for astigmatism. Monocular BCVA improved from 0.56±0.23 to 0.51±0.23 Log MAR (P=0.007), and binocular BCVA improved from 0.54±0.25 to 0.48±0.24 Log MAR (P=0.01) after fitting RGPCL. Following the use of RGPCL, contrast sensitivity was significantly improved at low (P=0.02) and intermediate (P< 0.001) frequencies but not at high frequencies (P=0.6). The frequency, amplitude, and intensity of nystagmus were decreased significantly after RGPCL use (P<0.001). Conclusion: RGPCL improved monocular and binocular BCVA and contrast sensitivity in hyperopic patients with infantile nystagmus syndrome. Motor indices of nystagmus (frequency, amplitude, and intensity) were also significantly improved after RGPCL use.

Visual rehabilitation using mini-scleral contact lenses after penetrating keratoplasty.

To report the visual rehabilitation outcomes and complications of patients fitted with mini-scleral rigid gas-permeable (RGP) contact lenses (mini-SCLs) after penetrating keratoplasty. We retrospectively reviewed 27 eyes (21 patients) that were fitted with mini-SCLs between October 2013 and December 2014. We analyzed demographic data, previous corneal disorders, visual outcomes, interval from keratoplasty to contact lens fitting, topographic and specular microscope data, fitted contact lens parameters, and complications. The patients were divided into two groups according to the elapsed time since surgery: Group A, grafts with <10 years (n=14 eyes); and Group B, grafts with ≥10 years (n=13 eyes). Lens use was discontinued in four eyes, and microbial keratitis developed in one eye during follow-up. No corneal graft rejection was observed. The mean interval between grafting and initial contact lens fitting was 10.6 ± 7.3 years (range: 1-29 years). The most frequent reason for keratoplasty was keratoconus (22 eyes, 81.4%). The mean contact lens-corrected visual acuity (CLCVA) was 0.09 ± 0.12 logMar (range: 0.50-0.00 logMar). The average topographic astigmatism, mean steepest keratometry (Kmax), and average cellularity on specular microscopy were 6.19 ± 3.49 diopters (D), 58.4 ± 7.8 D, and 1,231 ± 723 cells/mm2, respectively. Mini-SCL use allowed successful visual rehabilitation after corneal keratoplasty, particularly in patients who required corrective lenses for low visual acuity and were unable to wear RGP contact lenses. Our results indicate that mini-scleral lenses may be an option for the treatment of corneal irregularities, such as those associated with keratoplasty.

Effects of Ocular Parameters on Diameter of Well-fitted Rigid Gas Permeable Lens in Koreans

Effects of Ocular Parameters on Diameter of Well-fitted Rigid Gas Permeable Lens in Koreans

Наш опыт оптической коррекции последствий радиальной кератотомии с помощью склеральных линз. Клинические случаи

Сlinical cases of rigid gas permeable lenses prescribed to the patients after radial keratotomy in the remote period are presented. The efficacy of optical correction of induced ametropias by scleral lenses is shown. Comfort sensation and high visual acuity make scleral lenses the main optical correction method for patients with irregular corneas // Russian ophthalmological journal. 2017; 10 (2): 92-6. (in Russian). doi: 10.21516/2072-0076-2017-10-2-92-96.

An observational cross-sectional study on the corneal endothelium of medium-term rigid gas permeable contact lens wearers.

To assess if polymegethism and pleomorphism were evident in corneal endothelium after medium-term rigid gas permeable (RGP) contact lens wear. In a cross-sectional observational study over 12 years, single images of the central region of the corneal endothelium of one eye of 46 subjects were taken with a non-contact specular microscope, along with a measure of central corneal thickness (CCT). The images were printed onto A3-sized paper and 100 cells/image measured by planimetry. Subjects aged between 20 and 32 years, with an average cumulative RGP wear of 6.0+/- 1.6 years (range 3-9 years) were assessed; 26 of the subjects were Caucasian and 20 were Asian. The mean CCT was 0.515+/- 0.027mm. The group cell area value was 401+/- 42 sq micron to give an estimated endothelial cell density (ECD) of 2520+/- 273 cells/sq mm. As compared to a historical database, most endothelia (37/46) showed some changes with the mean coefficient of variation on cell area (COV) being 36.7+/- 8.0% and the percentage of 6-sided (HEX) being 51.8+/- 8.8%. There were modest correlations between years of RGP wear and both COV (p=0.009, r spearman=0.424) and HEX (p=0.025, r spearman=-0.291), but not for ECD or CCT. Corneal endothelial polymegethism appears to be a commonplace consequence of RGP lens wear with the magnitude of the change being related to the cumulative duration of the lens wear.

Effects of Lead Phytochemicals of Radix Scutellariae on Acanthamoeba.

Acanthamoeba keratitis (AK), which is associated with noncompliant use of contact lenses, remains difficult to treat due to delayed diagnosis and paucity of therapeutic agents. Although improvements in activity against Acanthamoeba infection have been achieved in disinfecting solutions for soft contact lenses, such modifications have not been extended to those for special rigid gas permeable (RGP) contact lenses, which are increasingly used for myopia control in children. Phytochemicals present in herbs used for traditional Chinese medicine may be effective as therapeutic or preventive agents. The purpose of this study was to investigate amoebicidal properties of lead phytochemicals of Radix scutellariae alone and in combination with multipurpose (disinfecting) solutions (MPS) for RGP lenses. Viability of Acanthamoeba castellani and A. polyphaga trophozoites was determined following exposure to four phytochemicals: baicalin, baicalein, wogonoside, and oroxylin A and both alone and in combination with four RGP MPS, using a modified stand-alone technique. As individual agents, wogonoside and oroxylin A showed highest activity against A. castellani and A. polyphaga trophozoites, respectively. For both organisms, the combination of baicalein and oroxylin A was superior. Effectiveness of MPS alone did not exceed 0.27 log reduction, but addition of combined baicalein and oroxylin A resulted in 0.92 and 0.64 log reductions of A. castellani and A. polyphaga, respectively. The combination of baicalein and oroxylin A enhanced the activity of MPS for RGP contact lenses against trophozoites of two pathogens, A. castellani, and A. polyphaga, and offers a potential therapeutic and/or preventative agent for AK.

Plasma graft of poly(ethylene glycol) methyl ether methacrylate (PEGMA) on RGP lens surface for reducing protein adsorption**The study was supported by National Natural Science Foundation of China (No. 51273072).

Poly(ethylene glycol) methyl ether methacrylate (PEGMA) was grafted on fluorosilicone acrylate rigid gas permissible contact lens surface by means of argon plasma induced polymerization to improve surface hydrophilicity and reduce protein adsorption. The surface properties were characterized by contact angle measurement, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy respectively. The surface protein adsorption was evaluated by lysozyme solution immersion and XPS analysis. The results indicated that a thin layer of PEGMA was successfully grafted. The surface hydrophilicity was bettered and surface free energy increased. The lysozyme adsorption on the lens surface was reduced greatly.

Modeling Corneal Oxygen with Scleral Gas Permeable Lens Wear.

The main goal of this current work is to use an updated calculation paradigm, and updated boundary conditions, to provide theoretical guidelines to assist the clinician whose goal is to improve his or her scleral gas permeable (GP) contact lens wearing patients' anterior corneal oxygen supply. Our model uses a variable value of corneal oxygen consumption developed through Monod equations that disallows negative oxygen tensions within the stroma to predict oxygen tension at the anterior corneal surface of scleral GP contact lens wearing eyes, and to describe oxygen tension and flux profiles, for various boundary conditions, through the lens, tears, and cornea. We use several updated tissue and boundary parameters in our model. Tear exchange with GP scleral lenses is considered nonexistent in this model. The majority of current scleral GP contact lenses should produce some levels of corneal hypoxia under open eye conditions. Only lenses producing the thinnest of tear vaults should result in anterior corneal surface oxygen tensions greater than a presumed critical oxygen tension of 100 mmHg. We also find that corneal oxygen tension and flux are each more sensitive to modification in tear vault than to changes in lens oxygen permeability, within the ranges of current clinical manipulation. Our study suggests that clinicians would be prudent to prescribe scleral GP lenses manufactured from higher oxygen permeability materials and especially to fit without excessive corneal clearance.

Keratokonus – the killing application for most contact lenses is the prototypical job for sclerals

SummaryUse of blown glass shells, the precursors of scleral lenses, for management of keratoconus was first described in the late 1800's. Keratoconus has been a leading indication for scleral lenses throughout the history of the devices, both prior to and following the introduction of rigid gas permeable scleral lenses in 1983. Scleral lenses offer several benefits compared to corneal lenses for primary corneal ectasia. They do not require alignment with a highly irregular corneal surface, and are instead supported by the conjunctival tissue overlying the relatively regular sclera. They offer excellent comfort and lens stability. Scleral lenses do not touch the cornea, so may be less likely to lead to corneal epitheliopathy or scarring. Unlike corneal transplantation, scleral lenses can immediately provide improvement in the quality of vision, and are considerably less invasive. Furthermore, scleral lenses may provide improved ocular comfort for patients with concurrent keratoconus and atopic disease of the lids and adnexa. This presentation will review and summarize visual and ocular outcomes of scleral lens therapy for management of exposure keratopathy at the Mayo Clinic.

Are scleral lenses safe for the meibomian gland?

SummaryNowadays, we are experiencing scleral lens rebirth through the development of new designs and materials respecting the anterior ocular surface represented by the cornea, the limbus and the anterior bulbar conjunctiva. But what about the posterior ocular surface, represented by the tarsal conjunctiva, the lid margin and meibomian glands? The interaction of the scleral lens with the posterior ocular surface will be assessed clinically in keratoconus patients wearing scleral lens for more than 2 years and compared in a randomized manner with soft lens, hybrid lens and corneal rigid gas permeable lens wearers and with control sample. Lid wiper epitheliopathy grade, tear film break up time, quality of meibum and meibomian gland trophicity will be compared between different groups…

Comparison of Rigid Gas Permeable and Toric Soft Lens for Correcting Astigmatism

Background: To compare visual acuity correction of astigmatism and comfort between toric softcontact lens and rigid gas permeable. Thus, ophthalmologists will less reluctantly propose contactlenses for the patients with astigmatism, and maximize the potential advantages of contact lenses forthe wearer.Methods: Literature review of all prospective and retrospective studies which reported managementof astigmatism with rigid gas permeable of toric soft contact lenses. The articles were divided intocharacteristics and outcomes. Outcomes reviewd were visual acuity, lens fit characteristics, cornealstaining, and subjective problems.Results: Lens corrected visual acuity by toric soft lens showed variation, which 3 studies reported afew amount of visual loss from spectacles corrected. Meanwhile other studies reported better toric softlens corrected visual acuity than spectacles. In RGP group, four studies reported better or the samevisual acuity with spectacles, and only one study showed a few amount of visual loss. Visual clarityand poor comfort were the most frequent subjective problems in toric soft lens group. Meanwhile,dryness and poor comfort were the most frequent subjective problems in RGP group.Conclusion: RGP is superior than toric soft lens in correcting astigmatism. Meanwhile, toric soft lensprovides quick adaptation and comfort. Keywords: astigmatism, rigid gas permeable, toric soft lens

Corneal aberration changes after rigid gas permeable contact lens wear in keratokonic patients

PurposeTo determine the short-term effect of rigid gas permeable (RGP) contact lenses on corneal aberrations in keratoconic patients. MethodSixteen keratoconic eyes with no history of RGP lens wear were included. They all had corneal aberrometry using Pentacam, and different aberration indices of the anterior and posterior surfaces of the cornea were measured before and 3 months after fitting RGP lenses. The effect of baseline parameters on these changes was tested in univariate and multiple models. ResultsTotal aberrations and individual Zernike coefficients did not show statistically significant changes after using RGP lenses. Although not statistically significant, vertical coma decreased in the anterior (p = 0.073) and posterior surface (p = 0.095). Relationships that remained statistically significant in the multiple model were between baseline central corneal thickness and changes in total higher order aberrations and anterior 4th order astigmatism 0°, and between baseline 2nd order astigmatism 45° and its changes. ConclusionIn this study, corneal aberrations remained unchanged 3 months after wearing RGP contact lens. Further studies with sufficient samples in different groups of keratoconus severity or baseline aberrations are needed to obtain more accurate results.

Dual-Polymer Drops, Contact Lens Comfort, and Lid Wiper Epitheliopathy.

ABSTRACTPurposeThis study compared a new contact lens rewetting drop containing both carboxymethylcellulose and hyaluronic acid (CMC-HA) with a standard drop containing carboxymethylcellulose only (CMC). Symptoms of discomfort typical in lens wear and lid wiper epitheliopathy (LWE) were assessed over a 3-month period in a diverse sample of contact lens wearers.MethodsAdapted daily-wear contact lens subjects using hydrogel, silicone hydrogel, or rigid gas permeable lenses were enrolled in this prospective, randomized, double-masked, parallel-group, 90-day study conducted at 15 clinical sites. Subjects were randomized 2:1 to CMC-HA (n = 244) or CMC alone (n = 121) with dosage at least four times per day, along with their habitual lens care system. At baseline and at days 7, 30, 60, and 90, subject-completed questionnaires, bulbar conjunctival staining, LWE, contact lens distance visual acuity (CLDVA), and standard safety measures were assessed.ResultsAt day 90, CMC-HA performed significantly better than CMC in ocular symptoms including dryness throughout the day (p = 0.006), and burning/stinging throughout the day (p = 0.02) and at the end of the day (p < 0.001). CMC-HA also performed numerically better for dryness at the end of day (p = 0.06). LWE staining was improved in the CMC-HA group at day 90 whereas it increased slightly in the CMC alone group, with a significant between-group difference (p = 0.009). CMC-HA also demonstrated greater reduction in conjunctival staining compared with CMC alone at day 90 (p = 0.08). No differences in CLDVA, contact lens wear time, acceptability, and product use were observed, and safety outcomes were similar between groups.ConclusionsThe addition of HA to a standard CMC rewetting drop improves clinical performance. In this comparison of rewetting drop efficacy in contact lens wearers, LWE was a useful clinical sign for differentiating clinical performance.

Blepharoplasty: One Touch - Serious Complication

1.1.Purpose:To describe and analyze a serious corneal complication following bilateral (4 lid) blepharoplasty by a plastic surgeon on patient with ultimate eye. 1.2.Case:A 59-year-old male with complicated eye history of pathological myopia, bilateral cataract surgery (June and September 2011) on both eyes and right eye vitrectomy (December 2012) following retinal detachment, decided to improve his esthetic appearance. After the plastic surgery procedure he had significantly decreased vision in his good eye. He was examined by an ophthalmologist 6 days after the plastic surgery and was diagnosed with severe bacterial conjunctivitis and a corneal foreign body. After adequate treatment it took 48 hours for the infection to be controlled but on biomicroscopy, although the cornea was absolutely clear, a strange linear lesion was identified. This lesion was apparently a result of electro-knife touch and was a reason for very poor vision of 0.1, which would not improve even with a pinhole. Corneal topography revealed 8 diopters irregular astigmatism. Anterior OCT demonstrated structural damage resulting in the reduction of corneal thickness to one half of its original size. In vivo confocal microscopy demonstrated a local area of keratocyte loss, with activation of the surrounding keratocytes. RGP lens improved the vision to useful 0.9, as the fellow eye had vision of 0.4 with notable metamorphopsia. 1.3.Conclusion:Although the complications of lower lid noninvasive blepharoplasty appear to be minimal, in the reported case corneal damage had a significant negative quality of vision and life impact. Protection of the eye surface and extreme care for the delicate anterior eye structures should be taken during surgery.

구면 및 비구면 RGP렌즈 피팅 시 각막 이심률별 눈물분포 비교

목적: 구면 및 비구면 RGP렌즈 피팅 시 각막 이심률별 눈물양 및 눈물분포를 비교하고자 하였다. 방법: 안질환 및 안과적 수술경험이 없는 20~30대 77명(136안)을 대상으로 가장 양호한 상태로 구면 및 비구면 RGP렌즈를 피팅하였다. 피팅된 RGP렌즈의 중심부, 중간주변부 및 주변부의 플루레신으로 염색된 눈물의 농도를 분석하여 눈물량을 분석하였고 이심률별로 눈물분포의 차이를 분석하였다. 결과: 구면 RGP렌즈 피팅 시 이심률 e < 0.38 범위와 <TEX>$0.68{\leq}e$</TEX> 범위는 중심부부터 주변부까지의 눈물분포량이 통계적으로 차이가 없어 다른 이심률 각막보다 상대적으로 고른 눈물분포량을 보이는 것으로 나타났다. 비구면 RGP렌즈의 경우는 구면 렌즈에 비해 중심부와 주변부의 눈물분포량 차이가 적었으며, 이심률 범위 0.48 < e < 0.68 각막에서는 두 렌즈 디자인 간에 통계적으로 유의한 눈물분포 차이가 나타났다. 즉, 이심률 범위 <TEX>$0.48{\leq}e</TEX><TEX><</TEX><TEX>0.68$</TEX> 범위의 각막은 비구면 RGP렌즈 피팅 시, 이심률 <TEX>$0.68{\leq}e$</TEX> 범위에서는 구면 RGP렌즈 피팅 시 더 고른 분포를 보였다. 또한 이심률이 증가할수록 중간주변부 눈물양이 증가하는 것으로 나타났다. 결론: 구면 및 비구면 RGP 렌즈 부분별 눈물양 및 눈물분포는 각막 이심률에 영향을 받기 때문에 각막 이심률에 따른 적절한 RGP렌즈 디자인의 선택이 필요함을 제안한다. Purpose: The present study was aimed to compare the tear volume and distribution by corneal eccentricity when fitted with spherical and aspherical RGP lenses. Methods: Spherical and aspherical RGP lenses were fitted in best alignment on a total of 77 subjects (136 eyes) in their twenties and thirties without any ocular disease or ocular surgery experience. The tear volume was analyzed by estimating the concentration of tear stained with fluorescein in the center of RGP lens as well as at the mid-peripheral and peripheral areas, and the difference of tear distributions was analyzed according to corneal eccentricity. Results: Tear distribution from the center to the peripheral area was not significantly different when spherical RGP lenses were fitted on the corneal eccentricities of e < 0.38 and <TEX>$0.68{\leq}e$</TEX>, indicating the relatively even tear distribution compared with other corneal eccentricity. In the case of aspherical RGP lenses, the difference of tear distribution between the central and peripheral areas was smaller than spherical RGP lenses. The significant difference of tear distribution according to RGP lens design was observed in the corneal eccentricity of 0.48 < e < 0.68. In other words, more even tear distribution was shown when aspherical RGP lenses were fitted on the cornea with eccentricity of <TEX>$0.48{\leq}e</TEX><TEX><</TEX><TEX>0.68$</TEX> and spherical RGP lenses were fitted on the cornea with eccentricity <TEX>$0.68{\leq}e$</TEX>. Furthermore, tear volume in the mid-peripheral area increased with higher corneal eccentricity. Conclusions: The results suggest that the appropriate selection of RGP lens design according to corneal eccentricity is necessary since tear volume and distribution by the regions of spherical and aspherical lenses are affected by corneal eccentricity.

Estimation of the hybrid lens parameters through rigid gas permeable lens fitting

PurposeTo estimate the fitting parameters of the hybrid contact lens in patients with corneal ectasia using the rigid gas permeable (RGP) lens. MethodsThirty-four eyes with corneal ectasia were evaluated in this study. The patients were examined once with the RGP lens and once with the hybrid contact lens. The relationship between the base curvature of the RGP and the vault of the hybrid lens and the correlation between their powers were analyzed. ResultsWe found a linear relationship between the base curvature of the RGP lens and the vault of the hybrid lens (P < 0.001) (R2 = 0.45). Moreover, we found a correlation between the power of the RGP and hybrid lens (P < 0.001) (R2 = 0.4). However, a 0.5 mm decrease in the base curvature radius of the RGP lens increased the vault of the hybrid lens by 72 μ. ConclusionThe results of this study could be used for better and faster selection of the first hybrid contact lens.

The influence of rigid gas permeable lens wear on the concentrations of dinucleotides in tears and the effect on dry eye signs and symptoms in keratoconus.

To evaluate the signs and symptoms of dry eye and dinucleotide secretion in tears of keratoconus patients (KC) and the potential effect of rigid gas permeable (RGP) contact lens wear. Twenty-three KC patients and forty control subjects were enrolled in this study. Signs of dry eye including tear volume, tear stability and corneal staining along with symptoms were assessed using the McMonnies questionnaire. Tears were collected using Schirmer strips, and dinucleotide concentrations in collected tears measured using high pressure liquid chromatography. Values obtained in KC and controls were compared. The effect of contact lens wear in KC was also assessed. KC eyes showed a significantly lower tear volume compared to controls, shorter tear break up time (TBUT), higher corneal staining and higher McMonnies dry eye questionnaire scores (p<0.05). When compared with non-wearers, KC contact lens wearers showed significantly higher symptoms, lower Schirmer and TBUT values (p<0.05). Concentration of Ap4A (0.695±0.304μM vs. 0.185±0.178μM) and Ap5A (0.132±0.128μM vs. 0.045±0.036μM) were higher in KC compared to controls (p<0.001) and only Ap4A was statistically higher in RGP wearers compared to non-wearers (0.794±0.478μM vs. 0.417±0.313μM) (p<0.05). Signs and symptoms of dry eye as well as concentrations of Ap4A and Ap5A were markedly increased in KC patients compared to controls. Moreover, Ap4A and symptoms of dry eye were statistically higher in RGP wearers compared to non-wearers. This seems to indicate that factors such as RGP contact lens wear might exacerbate the clinical condition of dry eye.

Replacing Gas Permeable Lenses: The Benefit of a Professional in Office Dispense

Replacing Gas Permeable Lenses: The Benefit of a Professional in Office Dispense