Rigid gas permeable contact lenses (RGP) are the most efficient means of providing optimal vision in keratoconus. RGP fitting can be challenging and time-consuming for ophthalmologists and patients. Deep learning predictive models could simplify this process.
To develop a deep learning model to predict the base curve (R0) of rigid gas permeable contact lenses for keratoconus patients.
We conducted a retrospective study at the Rothschild Foundation Hospital between June 2012 and April 2021. We included all keratoconus patients fitted with Menicon Rose K2® lenses. The data was divided into a training set to develop the model and a test set to evaluate the model\'s performance. We used a U-net architecture. The raw matrix of anterior axial curvature in millimeters was extracted from Scheimpflug examinations for each patient and used as input for the model. The mean absolute error (MAE) between the prediction and the prescribed R0 was calculated. Univariate and multivariate analyses were conducted to assess the model\'s errors.
Three hundred fifty-eight eyes from 202 patients were included: 287 eyes were included in the training dataset, and 71 were included in the testing dataset. Our model\'s Pearson coefficient of determination (R2) was calculated at 0.83, compared to 0.75 for the manufacturer\'s recommendation (mean keratometry, Km). The mean square error of our model was calculated at 0.04, compared to 0.11 for Km. The predicted R0 MAE (0.16 ± 0.13) was statistically significantly different from the Km MAE (0.23 ± 0.23) (p = 0.02). In multivariate analysis, an apex center outside the central 5 mm region was the only factor significantly increasing the prediction absolute error.
Our deep learning approach demonstrated superior precision in predicting rigid gas permeable contact lens base curves for keratoconus patients compared to the manufacturer\'s recommendation. This approach has the potential to be particularly beneficial in complex fitting cases and can help reduce the time spent by ophthalmologists and patients during the process.

The aim of this prospective cross-sectional cohort study was to test the effect of silicone hydrogel (SH) and rigid gas permeable (RGP) contact lens (CL) wear on corneal sensitivity, applying the new Swiss Liquid Jet Aesthesiometer for Corneal Sensitivity (SLACS) and the Cochet-Bonnet (CB) aesthesiometer, based on subject feedback (psychophysical method).
Participants were recruited for three equally large groups: Group A (SH CL), Group B (RGP CL) and Group C (non-CL wearers). Inclusion criteria were healthy eyes and OSDI ≤ 13. Corneal sensory thresholds were determined twice during two visits, with aid of SLACS and CB.
96 participants completed the study (n = 33 in groups A and C, n = 30 in group B); average age in group A: 27.42 ± 6.83 years, group B: 36.90 ± 9.68 years and group C: 26.06 ± 6.19 years. No statistically significant difference in corneal sensitivity was observed between the three groups for either method (p = 0.302 for SLACS, p = 0.266 for CB; Kruskal-Wallis rank sum test). Higher CSTs were obtained for males than for females in both CL groups with SLACS, and with CB only in the RGP CL group (p = 0.041 in Group A, p = 0.006 in Group B with SLACS; p = 0.041 in Group B with CB; bootstrap analysis with age correction and gender balancing). No correlation was observed between CL comfort and corneal sensitivity for neither method applied (for SLACS r = 0.097 and p = 0.51, for CB r = 0.17 and p = 0.15; robust linear mixed model).
No difference in corneal sensitivity with CL compared to non-CL wear was noted in this study. However, lower levels of corneal sensitivity were observed in the male CL groups, warranting further investigation.

OBJECTIVE: To evaluate the effect of rigid gas permeable contact lens (RGP-CL) on corneal morphological parameters and vision-related quality of life in keratoconus (KC) patients.
METHODS: Totally 57 eyes of 30 KC patients who were followed-up for more than two years, including 17 RGP wearers (32 eyes) and 13 non-wearers (25 eyes) were retrospectively analyzed. Initial medical history and corneal topography were collected at baseline. Corneal topography, corneal aberration, optical coherence tomography, and vision-related quality of life questionnaires were performed at the last follow-up.
RESULTS: According to corneal topography, increase of the flattest keratometric values was higher in RGP wearers than in non-wearers (P=0.038). The morphological parameters, including symmetry index of front corneal curvature (P=0.004) and Baiocchi-Calossi-Versaci index front (P=0.047), were lower in RGP wearers than in non-wearers. Vertical coma was smaller in RGP wearers than non-wearers in 3.0, 5.0, 6.0, and 7.0 mm pupil diameters, respectively (P<0.05). The environmental triggering domain of ocular surface disease index was worse in RGP wearers as compared to non-wearers (P=0.003). At the last follow-up, there were no significant differences in constituent ratios of KC progression, corneal thickness topography, epithelial thickness topography, morphological parameters of corneal topography, and other questionnaire scores between the two groups (all P>0.05).
CONCLUSIONS: Long-term use of RGP does not worsen KC but may cause corneal epithelial remodeling to increase symmetry of corneal anterior surface, reduce corneal vertical coma and improve visual quality. However, RGP wearing causes a slight decrease in vision-related quality of life. The occurrence of ocular surface symptoms is mainly associated with environmental triggering factors.

The study assessed the contact lens prescribing patterns and associated factors in a university optometry clinic in Trinidad and Tobago. The data relating to habitual or new contact lens (CL) prescribing patterns among wearers over a two-year period were reviewed. Pearson\'s chi-squared test and logistic regression models were used to analyze the findings. The Hosmer-Lemeshow goodness-of-fit test was used to examine the model calibration. A total of 243 CL fits were analyzed, and the Homeshow-Lemeshow goodness-of-fit test indicated a good fit (χ2 (7) = 7.296, p = 0.399). The mean age of lens wearers was 29.6 ± 12.4 (mean ± SD); the majority, 155 (63.8 %) of whom, were 21 to 40 years old. Most lenses were fitted on females (64.2% of fits overall) and about half of the wearers (n = 122, 50.2%) were prescribed lenses for cosmetic purposes. Conventional soft CL were the most prescribed modality of wear, accounting for 129 (53.1%) of the fits. Age from 21 to 40 years was the predictor of lens type prescribed, and those in that age range were four times more likely to be prescribed soft lenses compared to other ages. The patterns of CL prescribing in a university optometry clinic in Trinidad and Tobago are similar to the global market trends with slight variations.

BACKGROUND: Rigid gas permeable (RGP) contact lenses implanted in the upper eyelid may remain asymptomatic. It is important to evert the upper eyelid even in the absence of definite pain.
METHODS: A 74-year-old woman with a history of rheumatoid arthritis visited a local clinic because of right eye discomfort that had persisted for 5 months. Eversion of the upper eyelid revealed an embedded foreign body, and she was referred to our hospital. A transparent and smooth-surfaced foreign body was found embedded at the center of the upper eyelid conjunctiva. Additionally, fatty tissues were found behind the foreign body. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a foreign body rich in water at the same site. The foreign body was a spherical object with a diameter of 9 mm reaching as deep as the tarsus. On removal, the foreign body was identified as an RGP contact lens. On further questioning, it was discovered that the patient had lost an RGP contact lens 7 years earlier. The symptoms disappeared after removal of the foreign body.
CONCLUSIONS: RGP contact lenses are not detected on MRI scans, but cysts around the lenses are detected, which may result in multiple detections. CT cannot differentiate a foreign body from granulation tissue. The foreign body itself or a reactive granuloma can be seen when the eyelid is everted.
CONCLUSIONS: A contact lens embedded in the eyelid without symptoms is rare but can be detected via a detailed interview, visual examination, and diagnostic imaging.

OBJECTIVE: To simplify the fitting process, this study was designed to predict the initial power of contact lenses using the regression model based on manual Javal keratometry data and refractive errors.
METHODS: In this retrospective study, 121 eyes of 69 patients with keratoconus (KCN) were fitted with a specific trial set of rigid gas permeable contact lenses based on the standard criterion of \"three-point touch\" over a 7-year period. Power of the cornea was measured using Javal keratometer. Refractive errors and over refraction of patients were diagnosed using Topcon autorefractometer (RM-A2000) and confirmed by Heine beta 2000 retinoscope.
RESULTS: The results of multiple linear regression showed the following equation: power of contact lens = -14.368 (constant of the final multiple regression model), +0.475 (spherical refraction), and +0.275 (flatter corneal power).
CONCLUSIONS: The results of this study revealed that lens power has a significant relationship with the power of the flat corneal meridian and spherical refractive error in KCN patients. The obtained regression model can be used to shorten patients\' chair time and optometric examination for predicting the power of contact lens.

OBJECTIVE: This study aimed to evaluate the structural changes in meibomian glands (MGs) and meibomian gland dysfunction (MGD)-associated ocular surface alterations in contact lens (CL) wearers.
METHODS: This prospective, multi-center, cross-sectional study included 44 soft CL wearers, 21 rigid CL wearers, and 26 healthy non-wearers. After completing the Ocular Surface Disease Index (OSDI) questionnaire, the participants were examined for lid margin abnormalities, tear breakup times, ocular surface staining, meibum quality and expressibility. Afterwards upper and lower eyelid meibography and Schirmer I test were performed.
RESULTS: A total of 91 participants (64 females and 27 males) (91 eyes) were classified into three groups. The mean percentage of meibomian gland loss (PMGL) was 25.3 ± 12.5 % in soft CL wearers, 34 ± 13.4 % in rigid CL wearers, and 18.4 ± 9.2 % in the control group. Mean OSDI score was higher in soft CL wearers (15.5 ± 18) than in the control group (3.5 ± 2.6) (p < 0.001) and the OSDI scores were correlated with mean PMGL in CL wearers (r = 0.411, p = 0.002, r = 0.588, p = 0.005, respectively). In soft CL wearers, the duration of CL use was the only predictive variable for mean PMGL in multivariate analysis. In a regression model including both CL groups, age and rigid CL material were predictive variables for mean PMGL.
CONCLUSIONS: CL use may cause MGD and this effect may be more pronounced in rigid CL wearers. In soft CL wearers, the duration of CL use is an important variable associated with MG loss, and subjective symptoms may guide the prediction of MG loss in these cases.

OBJECTIVE: To evaluate vision-related quality of life in keratoconus patients and associated impact of keratoconus severity indicators using the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25).
METHODS: This was a prospective cross-sectional study carried out from November 1, 2014, to April 30, 2015, in the corneal service of the Hôtel-Dieu hospital, Paris, France. A hundred and one keratoconus patients were consecutively enrolled. Participants completed a French-validated version of the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25). Manifest refraction, maximum keratometry value, and corneal thinnest point were recorded. Associations between clinical and demographic factors, previous medical or surgical treatment, and NEI-VFQ-25 scale scores were evaluated.
RESULTS: Vision-related quality of life was no better in patients managed with rigid gas permeable contact lens, collagen cross-linking, or intracorneal ring segment implantation, compared with untreated patients. In advanced keratoconus (stages II, III, and IV of Amsler-Krumeich classification), rigid gas permeable contact lens wearers had better general vision but more ocular pain. Distance-corrected visual acuity worse than 20/40, mean refractive cylinder > 2.5 diopters, and corneal thinnest point < 460 μm in the better eye were associated with a lower vision-related quality of life. In multivariate analysis, only the uncorrected and distance-corrected visual acuity of the better eye remained significantly correlated with vision-related quality of life.
CONCLUSIONS: Low distance-corrected visual acuity in the better eye was the strongest predictor of low vision-related quality of life.

BACKGROUND: Congenital cataract is currently one of the leading blindness-causing eye diseases in children. Surgical treatment only opens the visual pathway for children. The postoperative recovery of visual function is also dependent on effective optical correction and visual function training. In this study, we analyzed the changes in eye-related parameters, adverse events and the annual cost of rigid gas permeable contact lens (RGPCL) and spectacles correction in infants with monocular aphakia after congenital cataract surgery.
METHODS: To analyze the postoperative visual acuity, strabismus, nystagmus, myopic shift, globe axial length growth, adverse events, patient adherence to patching, and annual cost for patients with unilateral congenital cataract who underwent cataract surgery. Rigid gas permeable contact lenses or spectacles were used to correct aphakia after congenital cataract.
RESULTS: Of the 49 patients, 20 patients with unilateral aphakia who used RGPCL were in group 1. Group 2 comprised 14 patients with persistent fetal vasculature (PFV) who used RGPCL, and there were 15 patients with spectacles in group 3. In group 1, there were important improvements in visual acuity, strabismus and nystagmus. In groups 2 and 3, there were no significant improvements in visual acuity, strabismus or nystagmus. Patients with a good adherence to patching had better visual acuity after the operation than patients who did not, in groups 1 and 3. There were no significant differences in myopic shift or rate of globe axial length growth among the 3 groups. No patients in group 1 had ocular disease that affected visual acuity. The mean annual expenses of the RGPCL group was 3965 yuan, and the mean annual cost of spectacles was 1140 yuan to 2500 yuan.
CONCLUSIONS: RGPCL is a safe and effective optical correction method for patients with monocular aphakia after congenital cataract surgery. Spectacles are not an ideal optical correction. Using RGPCL to correct patients with PFV, the final visual acuity improved, but the difference was not statistically significant. There were no improvements in strabismus or nystagmus in patients with PFV.

OBJECTIVE: To determine the short-term effect of rigid gas permeable (RGP) contact lenses on corneal aberrations in keratoconic patients.
METHODS: Sixteen 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.
RESULTS: Total 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.
CONCLUSIONS: In 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.