The aim of this study is to analyze the anterior and posterior corneal surface shape and the corneal thickness difference outcomes between before and after scleral lens (ScCL) wear in post-LASIK ectasia subjects for one year. Twenty eyes with post-LASIK ectasia wearing scleral lenses were evaluated in a visit before contact lens and after 1, 6, and 12 months. The study variables analyzed included the apex, nasal, temporal, inferior, and superior corneal thickness; the anterior and posterior surface corneal at corneal diameters of 8, 6, 4, and 2 mm, and high-contrast visual acuity. A statistically significant increment of corneal thickness (p < 0.05) was observed in the inferior area after 6 months and in the superior area in the 12-month follow-up after wearing ScCLs. The anterior corneal curvature presented a flattening and a statistically significant steepening (p < 0.05) in the central and peripheral radii, respectively, after one year. The posterior corneal curvature showed a significant (p < 0.05) steepening, which mainly affected the central region after one year. Despite these changes, high-contrast visual acuity with ScCL correction remained at the same values. The prolonged use of scleral lenses in post-LASIK subjects showed significant changes in the corneal curvature and thickness. These outcomes recommend more detailed and periodic topographic and vision quality checks to monitor the wear in ScCL patients.

To compare the clinical outcomes of diffractive multifocal and monofocal lenses in post-laser in situ keratomileusis (LASIK) patients who underwent cataract surgery.
This was a retrospective, comparative study of clinical outcomes that was conducted at a referral medical center. Post-LASIK patients who underwent uncomplicated cataract surgery and received either diffractive multifocal or monofocal lens were studied. Visual acuities were compared at baseline and postoperatively. The intraocular lens (IOL) power was calculated with Barrett True-K Formula only.
At baseline, both groups had comparable age, gender, and an equal distribution hyperopic and myopic LASIK. A significantly higher percentage of patients receiving diffractive lenses achieved uncorrected distance visual acuity (UCDVA) of 20/25 or better (80 of 93 eyes, 86% vs. 36 of 82 eyes, 43.9%, P = 1.0 x 105) and uncorrected near vision of J1 or better (63% vs. 0) compared to the monofocal group. The residual refractive error had no significant difference (0.37 ± 0.39 vs. 0.44 ± 0.39, respectively, P = 0.16) in these two groups. However, more eyes in the diffractive group achieved UCDVA of 20/25 or better with residual refractive error of 0.25-0.5 D (36 of 42 eyes, 86% vs. 15 of 24 eyes, 63%, P = 0.032) or 0.75-1.5 D (15 of 21 eyes, 23% vs. 0 of 22 eyes, P = 1.0 x 10-5) compared to the monofocal group.
This pilot study shows that patients with a history of LASIK who undergo cataract surgery with a diffractive multifocal lens are not inferior to those who receive monofocal lens. Post-LASIK patients with diffractive lens are more likely to achieve not only excellent near vision, but also potentially better UCDVA, regardless of the residual refractive error.

In June 2020, a 28-year-old female patient was admitted to our clinic with reduced vision in the left eye. She had systemic COVID-19 infection in May 2020 and during her treatment course, her visual complaints had begun approximately 1 week after the beginning of the COVID-19. Previously, the patient had bilateral femtosecond assisted - Laser in situ Keratomileusis in our clinic in 2018. There was no previous history of herpetic eye involvement. In her examination, the uncorrected visual acuity was 20/20 in the right and 20/32 in her left eye. Slit-lamp examination revealed interlamellar infiltration at the flap interface in the left eye. Considering herpetic activation, ganciclovir ointment 5 × 1, valacyclovir tablet 2 × 1, and prednisolone acetate 1.0% eye drops 5 times a day and artificial tear 5 × 1 were started. Two weeks later, the infiltration completely resolved and the uncorrected visual acuity increased to 20/20.

OBJECTIVE: To compare central corneal thickness (CCT) measurements by scanning slit topography (SST), infrared pachymetry (IRP), and ultrasound pachymetry (USP), and their agreement in normal and post-laser in situ keratomileusis (LASIK) eyes.
METHODS: Sixty normal and 35 post-LASIK subjects were recruited. Only one eye from each subject was analyzed. Non-contact pachymetry was performed first, and the order for SST (Orbscan IIz) and IRP (Tonoref III) was randomized for each patient, to be followed by contact USP (Echoscan US-4000). Pearson\'s correlation, paired t test, and Bland-Altman plots were used to investigate association, difference, and agreement among different instruments respectively.
RESULTS: The measurements obtained with the instruments were highly correlated. Compared to CCT determined by USP (CCTUSP), CCT determined by SST (after correction with acoustic factor) (CCTSSTC) was thicker by 7 µm in normal eyes (P < 0.001). There was no significant difference between CCTSSTC and CCTUSP (P = 0.128), but a thickness-dependent deviation in post-LASIK eyes (P = 0.003). The CCT determined by IRP (CCTIRP) was thicker than CCTUSP in normal (P < 0.001) and post-LASIK eyes (P < 0.001) and demonstrated proportional overestimation with thinner corneas, with less predictable ultrasonic equivalent corneal thickness in normal eyes. Conversely, CCTIRP significantly underestimated CCT compared to CCTSST and showed increasing underestimation with thinner corneas in both normal and post-LASIK eyes (both P < 0.001).
CONCLUSIONS: Central corneal thickness determined by SST, IRP and USP were not interchangeable or interconvertible, probably attributed to difference in methodologies. Compensation with algorithms may improve agreements amongst instruments.

This study was designed to evaluate efficacy and stability of corneal collagen crosslinking (CXL) in halting the progression of post-laser in situ keratomileusis (LASIK) ectasia and provide long-term follow-up results with an average of 80mo. Patients with post-LASIK ectasia were treated with CXL between December 2007 and January 2012. Main outcome measures were uncorrected distance visual acuities (UDVA) and corrected distance visual acuities (CDVA), minimum and maximum keratometry (K) values, spherical and cylindrical refraction, and corneal thickness. The study evaluated 17 eyes for 13 patients (8 men, 5 women) with mean age of 31y (range 23 to 39) and mean follow-up of 80.7±15 (range 57 to 102)mo. UDVA and CDVA improved from logMAR 0.53±0.36 (20/63) to 0.49±0.4 (20/50) (P=0.43) and from 0.18±0.17 (20/28) to 0.16±0.16 (20/27) (P=0.55) respectively. In 15 eyes UDVA and in 13 eyes CDVA either remained stable or improved ≥1 Snellen lines (88.2%) and (76.5%) respectively. Although statistically insignificant, spherical and cylindrical refraction decreased post-CXL from -1.26±2.87 to -0.38±2.32 diopters (D) (P=0.054) and from -3.80±2.47 to -3.04±2.18 D (P=0.13) respectively. Kmax significantly decreased from 44.23±3.76 to 42.85±3.08 D (P=0.013) and Kmin decreased from 41.07±3.61 to 40.00±2.65 D (P=0.057). Corneal thickness decreased from 470±42 to 460±41 µm, but was statistically non-significant (P=0.063). Therefore, CXL is effective in halting and partially reversing the progression of post-LASIK ectasia on the long-term (mean follow-up of more than 80mo), thus highlighting the stability and maintained effect of CXL for such cases.

OBJECTIVE: To evaluate the relative proportion of conjunctival MUC5AC+ and MUC5AC- goblet cells in a post-LASIK population and their association with dry eye indicators and corneal nerve morphology using a MUC5AC+ Goblet Cell Index.
METHODS: Twenty subjects who had undergone LASIK > 12 months previously and 20 age-matched controls were recruited. Dry eye symptoms, tear breakup time, osmolarity, meniscus area and corneal nerve morphology were examined. Conjunctival impression cytology samples were collected from inferior-temporal bulbar conjunctiva using Millicell® inserts. Total goblet cell density was determined from positive cytokeratin-7 (CK7) immunolabelling; MUC5AC+ goblet cell density was determined from both CK7+- and MUC5AC+-immunolabelled cells. The ratio of MUC5AC+ to total density was defined as the \"MUC5AC+ Goblet Cell Index\". Differences in variables between groups and the associations between goblet cell variables and clinical assessments were examined.
RESULTS: No significant differences in the total and MUC5AC+ goblet cell density and tear film parameters were found between groups, although greater ocular discomfort was reported in the post-LASIK group (P = 0.02). A higher MUC5AC+ Index was associated with worse/greater dry eye symptoms (ρ = 0.55, P = 0.01) and higher nerve tortuosity (ρ = 0.57, P = 0.01) in the post-LASIK group; lower nerve density and thickness was found in controls (ρ > -0.45, P < 0.05), but not associated with tear film parameters.
CONCLUSIONS: The MUC5AC+ Goblet Cell Index provides an indicator of mucin secretion for assessing the goblet cell function in dry eye. In the post-LASIK participants, we found an increased MUC5AC+ Index associated with worse dry eye symptoms and adverse changes in corneal nerve morphology.

To test the hypothesis that marginal ray deviations determine perceived starburst sizes, and to explore different strategies for decreasing starburst size in highly aberrated eyes.
Perceived size of starburst images and visual acuities were measured psychophysically for eyes with varying levels of spherical aberration, pupil sizes, and defocus. Computationally, we use a polychromatic eye model including the typical levels of higher order aberrations (HOAs) for keratoconic and post-LASIK eyes to quantify the image quality (the visually weighted Strehl ratio derived from the optical transfer function, VSOTF) with different pupil sizes at both photopic and mesopic light levels.
For distance corrected post-LASIK and keratoconic eyes with a night-time pupil (e.g., 7 mm), the starburst diameter is about 1.5 degrees (1 degree for normal presbyopic eyes), which can be reduced to ≤0.25 degrees with pupil sizes ≤3 mm. Starburst size is predicted from the magnitude of the longitudinal spherical aberration. Refracting the eye to focus the pupil margin also removed starbursts, but, unlike small pupils, significantly degraded visual acuity. Reducing pupil diameter to 3 mm improved image quality for these highly aberrated eyes by about 2.7 ×  to 1.7 ×  relative to the natural pupils when light levels were varied from 0.1 to 1000 cd m-2 , respectively.
Subjects with highly aberrated eyes observed larger starbursts around bright lights at night predictable by the deviated marginal rays. These were effectively attenuated by reducing pupil diameters to ≤3 mm, which did not cause a drop in visual acuity or modelled image quality even at mesopic light levels.

OBJECTIVE: To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis (LASIK).
METHODS: One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea: steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism (Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation (Sw) the coefficient of repeatability (R), the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC). Agreement between instruments was tested with the Bland-Altman method by calculating the 95% limits of agreement (95% LoA).
RESULTS: In keratoconic eyes, the intra-examiner and inter-examiner ICC were >0.95. As compared with measurement by high-resolution Placido disk-based topography, the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf (0.32 vs 0.88), Ks (0.61 vs 0.88), and Km (0.32 vs 0.84) but higher for Ks-Kf (0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% LoA were -1.28 to +0.55 for Kf, -1.36 to +0.99 for Ks, -1.08 to +0.50 for Km, and -1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes, the intra-examiner and inter-examiner ICC were >0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf, 0.21 vs 0.88 for Ks, 0.17 vs 0.86 for Km, and 0.28 vs 0.33 for Ks-Kf. The inter-examiner R was 0.09 vs 0.64 for Kf, 0.15 vs 0.56 for Ks, 0.09 vs 0.59 for Km, and 0.18 vs 0.23 for Ks-Kf. The 95% LoA were -0.54 to +0.58 for Kf, -0.51 to +0.53 for Ks and Km, and -0.28 to +0.27 for Ks-Kf.
CONCLUSIONS: As compared with Placido disk-based topography, the high-resolution rotating Scheimpflug camera provides more repeatable and reproducible measurements of Ks, Kf and Ks in keratoconic and post-LASIK eyes. Agreement between instruments is fair in keratoconus and very good in post-LASIK eyes.

OBJECTIVE: To evaluate the efficacy and safety of conductive keratoplasty (CK) for the treatment of presbyopia and analyze the differences in the effects between post- and non-laser in situ keratomileusis (LASIK) eyes. Clinical preoperative factors that could affect the predictability of CK were also analyzed.
METHODS: The visual and refractive outcomes of CK for the treatment of presbyopia in 14 eyes of 13 post-LASIK patients (post-LASIK group mean age 50.9 ± 3.4 years) and those of 25 eyes of 25 non-LASIK patients (non-LASIK group mean age 52.4 ± 4.0 years) were studied. The clinical efficacy, safety, stability, and predictability of CK were statistically evaluated.
RESULTS: The mean (logarithm of the minimum angle of resolution [logMAR] ± standard deviation [SD]) of preoperative uncorrected near visual acuity (UNVA) and manifest refraction spherical equivalent (MRSE) were 0.64 ± 0.25 diopter (D) and 0.35 ± 0.48 D, respectively, in the post-LASIK group, and 0.71 ± 0.20 D and 0.64 ± 0.61 D, respectively, in the non-LASIK group. At 6 months after CK, the mean UNVA and MRSE were 0.07 ± 0.13 D and -1.59 ± 0.86 D, respectively, in the post-LASIK group, and 0.07 ± 0.12 D and -1.06 ± 0.56 D, respectively, in the non-LASIK group. At 1 year after CK, the mean UNVA and MRSE were 0.30 ± 0.17 D and -0.58 ± 0.52 D, respectively, in the post-LASIK group, and 0.28 ± 0.34 D and -1.56 ± 0.62 D, respectively, in the non-LASIK group. There was no significant difference between the two groups in either factor at 6 months postoperative (Student\'s t-test, P > 0.05). At 1 year after CK, all the treated eyes maintained corrected distance visual acuity better than -0.08 (logMAR). The mean cylindrical errors were within ±1.00 D in 100% of the post-LASIK and non-LASIK patients. As for the preoperative clinical factors evaluated for their potential relationship to the predictability of CK, none showed significant effect on the clinical outcomes.
CONCLUSIONS: CK is demonstrated to be safe for the treatment of presbyopia in post-LASIK patients as well as in non-LASIK patients, though needed longer observation in terms of factors affecting predictability.