Pupil size and quality of vision after LASIK

Analysis of Treatment Discontinuation in Orthokeratology: Studying Efficacy, Safety, and Patient Adherence Over Six Months

PURPOSE

This study aimed to evaluate the efficacy, safety, and participant compliance of orthokeratology treatment for the correction of myopic refractive errors over a six-month prospective study and to define the potential reasons for early treatment discontinuation.

METHODS

A total of 32 participants with low-to-moderate myopia were fitted with the spherical model of corneal refractive therapy (CRT) orthokeratology lenses (Paragon Vision Sciences) and followed over six months, with specific attention to alterations in refractive error, corneal topography, and epithelial thickness. Concurrently, participant feedback and reasons for any treatment discontinuation were documented.

RESULTS

Significant changes in refractive error and in corneal topography were observed, with approximately 50% of the refractive error being corrected on the first night of use and 100% by the first two weeks (P<0.001). Central epithelial thickness experienced substantial thinning, reducing to 15.65±4.49 μm (67.38%) (P<0.001) after 6 months of lens use. Six participants withdrew from this study for varied reasons, including unmet visual expectations and difficulty adhering to the lens-wearing regimen. Notably, the dropout group exhibited higher baseline low-order aberrations and less prolate corneas than those who persisted with the treatment (P<0.05).

CONCLUSION

Orthokeratology with CRT is efficacious and safe for the correction of low-to-moderate myopia in adults, but a portion of patients discontinue the treatment in the first 6 months of contact lens wear. Special care should be taken when recommending orthokeratology in patients with higher levels of myopia and corneas with less prolate shape, providing more realistic expectations and even changing to dual axis or more sophisticated designs.

Biometric factors associated with the postoperative visual performance of a multifocal intraocular lens

Purpose

To identify the biometric factors associated with postoperative visual performance after uneventful phacoemulsification with multifocal intraocular lens (MIOL) implantation.

Methods

In this retrospective cohort study, 72 eyes of 72 patients implanted with the HumanOptics Diff-aAY MIOL were included. Preoperative examination data including the white-to-white distance (WTW), anterior chamber depth (ACD), axial length and corneal astigmatism were gathered through the electronic medical records. One month postoperatively, the pupil parameters, corneal aberrations, corneal astigmatism, IOL tilts and IOL decentrations were measured using an OPD-Scan III aberrometer. Postoperative visual performance parameters were recorded as the visual acuity, depth of focus, modulation transfer function (MTF) and point spread function (PSF) values, area under log contrast sensitivity function (AULCSF), retinal straylight and visual function questionnaire scores. Univariate and multivariate linear regression analyses were then performed to evaluate the associations between the potential biometric factors and postoperative visual outcomes.

Results

Younger age predicted greater MTF and PSF values, better AULCSF and better retinal straylight (P < 0.05). A lower corneal trefoil predicted better MTF and PSF values (P < 0.05). Smaller IOL decentration predicted better distance-corrected near visual acuity, greater AULCSF and better retinal straylight (P < 0.05). A less negative spherical equivalent (SE) predicted better MTF values (P = 0.017), while a more negative SE predicted better Visual Function Index-14 (VF-14) questionnaire scores and satisfaction scores (P < 0.05). A higher IOL power predicted better best corrected distance visual acuity (P = 0.005). Lower preoperative corneal astigmatism predicted greater MTF values (P = 0.020). Lower postoperative corneal astigmatism, smaller corneal high-order aberrations (HOAs), smaller photopic pupil size, larger WTW and deeper ACD predicted a better AULCSF (P < 0.05).

Conclusions

IOL decentration, IOL power, age, preoperative and postoperative corneal astigmatism, SE, photopic pupil size, corneal trefoil, WTW, ACD and corneal HOAs were significantly associated with postoperative visual performance. These findings might aid in patient selection prior to MIOL implantation.

Pupil size measurements with a multifunctional aberrometer/coherence interferometer/tomographer and two infrared-based pupillometers

PURPOSE

To compare precision of pupil size measurements of a multifunctional device (Pentacam AXL Wave [Pentacam]) and 2 infrared-based pupillometers (PupilX, Colvard) and to compare repeatability of Pentacam and PupilX.

SETTING

Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany.

DESIGN

Prospective, comparative trial.

METHODS

Pupil diameter of healthy eyes was measured with Colvard once and Pentacam without glare (WO) and with glare (WG), PupilX in 0, 1, and 16 lux 3 times each. In a second series, measurements with Pentacam WO and PupilX in 0.06 and 0.12 lux were assessed.

RESULTS

36 eyes of participants aged 21 to 63 years were included. Mean pupil diameter was 6.05 mm with Colvard, 5.79 mm (first series), 5.50 mm (second series) with Pentacam WO, 3.42 mm WG, 7.26 mm PupilX in 0, 4.67 mm 1, 3.66 mm 16, 6.82 mm in 0.06, and 6.39 mm in 0.12 lux. Measurements with Pentacam WO were significantly different to PupilX in 0, 0.06, 0.12, and 1 lux (all P < .001), but not to Colvard ( P = .086). Pupil size measured with Pentacam WG and PupilX in 16 lux was not significantly different ( P = .647). Consecutive measurements with Pentacam WO and WG had mean SD of 0.23 mm and 0.20 mm, respectively, and with PupilX 0.11 in 0, 0.24 mm 1, and 0.20 mm in 16 lux.

CONCLUSIONS

Pentacam provided good assessment of pupil size but was not equivalent to PupilX in low lighting conditions. Repeatability was more favorable for Pentacam.

Illumination levels in commonly used ophthalmic devices

Pupil diameter is a key parameter for corneal and multifocal intraocular lens surgery. Many devices are dedicated to measure the pupil size, but do not specify the illumination during capture. The aim of this study was to present illumination levels in routinely used ophthalmic devices which present pupil sizes. To obtain measurements, the lux meter was placed in the chin rest in the corneal plane and the room was completely dimmed. Ten measurements were taken for each device. The illumination levels for white and red Placido disk corneal topographers were 1253.1 ± 0.2 and 329.0 ± 0.2 lux, respectively (both photopic conditions). Scheimpflug corneal tomography should be considered as a mesopic measurement (14.5 ± 0.1 lux). Optical coherence tomography and autorefractometry are scotopic measurements (0.4-0.6 lux). We postulate that producers should provide illumination levels of their devices measuring pupil size. Moreover, when mentioning a pupil size, one should consider presenting to what lighting conditions it refers to.

Characteristics of disk halo size and its correlation with lenticule quality in small incision lenticule extraction for moderate to high myopia

PURPOSE

To investigate changes in disk halo size after small incision lenticule extraction (SMILE) and the correlation between halo size and lenticule quality in moderate to high myopia.

METHODS

Thirty eyes of 30 consecutive patients (mean age, 24.9 ± 4.5 years; mean spherical equivalent, -6.85 ± 1.18 D) undergoing SMILE were included in this prospective study. Lenticule surface quality was accessed with a scanning electron microscopy by a scoring system. Halo size was measured preoperatively and at 1, 3, and 6 months postoperatively. Multiple linear regression analysis was performed to explore associations between halo size and a range of factors, including lenticule quality.

RESULTS

Disk halo size increased slightly at 1 month and then recovered continually from 3 to 6 months postoperatively, with no difference between halo size during the preoperative period and at 6 months postoperatively (P > 0.05). One month after SMILE, halo size (1 cd/m2, 5 cd/m2) was associated only with uncorrected distance visual acuity (P ≤ 0.004). A halo size of 5 cd/m2 at 3 months postoperatively correlated with the anterior surface quality of the lenticule (P = 0.046). At 6 months postoperatively, a halo size of 1 cd/m2 was associated only with the baseline, accounting for 11.9% of the variability (P = 0.041); no correlations were found for the halo size of 5 cd/m2.

CONCLUSIONS

Disk halo size after SMILE was enlarged at an early stage postoperatively and subsequently declined to the baseline level during a 6-month follow-up. The quality of the lenticule surface influenced halo size changes in the early phase.

Comparison of visual quality after SMILE correction of low-to-moderate myopia in different optical zones

OBJECTIVE

To compare the effects of different optical zones for small-incision lenticule extraction (SMILE) on postoperative visual quality in low-to-moderate myopia.

METHODS

This retrospective case-control study involved patients who underwent SMILE using two optical-zone diameters: 6.5 mm (50 patients, 100 eyes) and 6.8 mm (50 patients, 100 eyes). Uncorrected visual acuity (UCVA), best corrected visual acuity, spherical equivalent (SE), corneal higher-order aberrations (HOAs), and subjective visual-quality questionnaire scores were assessed.

RESULTS

Postoperatively, UCVA and SE did not differ between the two groups (P > 0.05). In both groups, corneal HOAs, spherical aberration, and coma significantly increased at 1 and 3 months postoperatively (P < 0.05), while trefoil was unchanged after surgery (P > 0.05). Corneal HOAs, spherical aberration, and coma significantly differed between the groups at 1 and 3 months (P < 0.05), while trefoil did not (P > 0.05). Visual-quality scores were higher in the 6.8 mm group than in the 6.5 mm group at 1 month (P = 0.058), but not at 3 months (P > 0.05). In both groups, subjective scores significantly decreased at 1 month (P < 0.05) and gradually returned to the preoperative level at 3 months (P > 0.05). The subjective visual-quality scores were negatively and positively correlated with pupillary and optical-zone diameter, respectively (P < 0.05 for both). Objective visual-quality indicators (HOAs, spherical aberration, and coma) were negatively correlated with optical-zone diameter (P < 0.05) but not pupillary diameter (P > 0.05).

CONCLUSION

SMILE in different optical zones effectively corrected low-to-moderate myopia. The larger the optical-zone diameter, the better the early postoperative visual quality.

Repeatability of pupil diameter measurements using three different topography devices

PURPOSE

To evaluate the intra- and inter-device repeatability of pupil diameter measurements using three different devices in patients prior to corneal refractive surgery.

METHODS

We examined preoperative measurements from a total of 204 eyes (102 patients) scheduled for corneal refractive surgery at two private centers between July and December 2021. Three consecutive scans were performed with three different devices (Sirius anterior segment analyzer, Pentacam HR, IOLMaster 500) in the same session by the same examiner under standardized conditions. To assess the intra- and inter-device repeatability, we calculated the Intraclass Correlation Coefficient (ICC) and demonstrated results using Bland-Altman plots.

RESULTS

The measurement accuracy (intra-device repeatability) of Sirius and IOLMaster was comparable (ICC = 0.64 and 0.61, respectively), with almost no statistically significant differences. Sirius showed the highest measurement accuracy among the three devices. Pentacam measurements resulted in lower precision, with an ICC of 0.09. The agreement between the pairs of devices (inter-device repeatability) was low (wide LoA ranges, Table 5).

CONCLUSION

In this study, the intra-device repeatability of Sirius and IOLMaster was higher than that of the Pentacam, although it did not achieve an optimal level across all three devices. The three devices examined cannot be used interchangeably.

Assessment of Pupil Size and Angle Kappa in Refractive Surgery: A Population-Based Epidemiological Study in Predominantly American Caucasians

Purpose This retrospective study aims to establish normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type in a largely Caucasian population in Utah, United States, utilizing the NIDEK OPD-Scan III system (Gamagori, Japan). Methods This study included 716 patients (1432 eyes) grouped based on spherical equivalence and age. Measurements were conducted under mesopic and photopic conditions. Statistical analysis involved Pearson's correlation and linear regression using the generalized estimating equation. NIDEK OPD-Scan III measured mesopic and photopic pupil size and angle kappa. The subjects were then grouped based on their spherical equivalence in diopters (D) and age in decades. The spherical equivalence groups were defined: >-6 D, -5.99 to -3 D, -2.99 to -0.25 D, -0.24 to 0.24 D, and >0.25 D (range 0.25-5.75 D). The higher-order aberration groups were based on the reason for the visit: laser-assisted in situ keratomileusis, photorefractive keratectomy, and small incision lenticule extraction as one group; cataract evaluation; and keratoconus. Astigmatism measurements were grouped into with-the-rule (WRT), against-the-rule (ATR), and oblique astigmatism, with further subgrouping into a young cohort (20-40 years) and an old cohort (>65 years).  Results Among 716 participants, 49.2% were men; the mean age was 42.1±15.5 (range 7-88 years). The average spherical equivalence for myopia eyes was -3.28±2.34 D, and 1.51±1.46 D for hyperopia eyes. The mean mesopic pupil size was 5.68 ± 1.09 mm; the photopic pupil size was 4.65±1.09 mm. Pearson's correlation coefficient for mesopic pupil size versus age was -0.551, and -0.42 for photopic pupil (p < 0.001); sphere vs mesopic pupil size was -0.200, and -0.173 for photopic pupil (p < 0.001). The regression analysis for mesopic pupil size versus age revealed a 0.39 mm decrease in average pupil size per decade increase in age, and 0.25 mm decrease per decade for photopic pupil. The regression analysis for mesopic pupil size versus sphere revealed a 0.22 mm decrease in average pupil size per 3D increase in sphere, and a 0.16 mm decrease 3 D increase in sphere for the photopic pupil. The mean mesopic angle kappa was 0.33 ± 0.15 mm; photopic angle kappa was 0.31±0.15 mm. Pearson's correlation coefficient for mesopic angle kappa vs spherical equivalence was 0.32, and 0.296 for photopic angle kappa (p <0.001 for both). Regression analysis for mesopic angle kappa vs spherical equivalence demonstrated a 0.051 mm increase in angle kappa per 3 D increase in spherical equivalence, and a 0.048 mm increase for photopic angle kappa (p < 0.001 for both). Among the higher-order aberration groups, the keratoconus group exhibited the highest levels. In terms of astigmatism type, WRT astigmatism was the most common in the young cohort, while ATR astigmatism was most prevalent in the older cohort. Conclusions The results of this study reveal significant associations between pupil size and increasing age, as well as between pupil size and increasingly positive refractive errors. These findings hold particular clinical relevance to older patients and individuals with hyperopia, as they undergo photoablative corneal refractive surgery or multifocal intraocular lens implantation. Understanding the established normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type can aid clinicians in making more informed decisions and improving patient outcomes.

Bibliometric and visualized analysis of myopic corneal refractive surgery research: from 1979 to 2022

Background

Myopic corneal refractive surgery is one of the most prevalent ophthalmic procedures for correcting ametropia. This study aimed to perform a bibliometric analysis of research in the field of corneal refractive surgery over the past 40 years in order to describe the current international status and to identify most influential factors, while highlighting research hotspots.

Methods

A bibliometric analysis based on the Web of Science Core Collection (WoSCC) was used to analyze the publication trends in research related to myopic corneal refractive surgery. VOSviewer v.1.6.10 was used to construct the knowledge map in order to visualize the publications, distribution of countries, international collaborations, author productivity, source journals, cited references, keywords, and research hotspots in this field.

Results

A total of 4,680 publications on myopic corneal refractive surgery published between 1979 and 2022 were retrieved. The United States has published the most papers, with Emory University contributing to the most citations. The Journal of Cataract and Refractive Surgery published the greatest number of articles, and the top 10 cited references mainly focused on outcomes and wound healing in refractive surgery. Previous research emphasized "radial keratotomy (RK)" and excimer laser-associated operation methods. The keywords containing femtosecond (FS) laser associated with "small incision lenticule extraction (SMILE)" and its "safety" had higher burst strength, indicating a shift of operation methods and coinciding with the global trends in refractive surgery. The document citation network was clustered into five groups: (1) outcomes of refractive surgery: (2) preoperative examinations for refractive surgery were as follows: (3) complications of myopic corneal refractive surgery; (4) corneal wound healing and cytobiology research related to photorefractive laser keratotomy; and (5) biomechanics of myopic corneal refractive surgery.

Conclusion

The bibliometric analysis in this study may provide scholars with valuable to information and help them better understand the global trends in myopic corneal refractive surgery research frontiers. Two stages of rapid development occurred around 1991 and 2013, shortly after the innovation of PRK and SMILE surgical techniques. The most cited articles mainly focused on corneal wound healing, clinical outcomes, ocular aberration, corneal ectasia, and corneal topography, representing the safety of the new techniques.

Quality of vision after myopic refractive surgeries: SMILE, FS-LASIK, and ICL

BACKGROUND

To characterize the quality of vision after SMILE, FS-LASIK, and ICL implantation and evaluate the related factors.

METHODS

131 eyes of 131 myopic patients (90 female, 41 male) who underwent refractive surgeries including SMILE (35 patients), FS-LASIK (73 patients), and ICL implantation (23 patients) were analyzed. The Quality of Vision questionnaires were completed 3 months after surgery, and the results were characterized and analyzed with baseline characteristics, treatment parameters, and postoperative refractive outcomes using logistic regression analysis to find out predicted factors.

RESULTS

Mean age was 26.5 ± 4.6 years (range: 18 to 39 years) and mean preoperative spherical equivalent was - 4.95 ± 2.04 diopters (D) (range: -1.5 to -13.5). Safety and efficacy index was comparable between different techniques: the safety index was 1.21 ± 0.18, 1.22 ± 0.18, and 1.22 ± 0.16 and the efficacy index were 1.18 ± 0.20, 1.15 ± 0.17, 1.17 ± 0.15 for SMILE, FS-LASIK and ICL respectively. The mean overall QoV score was 13.40 ± 9.11, with mean frequency, severity, and bothersome score of 5.40 ± 3.29, 4.53 ± 3.04, and 3.48 ± 3.18 respectively, and there was no significant difference between different techniques. Overall, the symptom with the highest scores was glare, following fluctuation in vision and halos. Only the scores of halos were significantly different among different techniques (P < 0.000). Using ordinal regression analysis, mesopic pupil size was identified as a risk factor (OR = 1.63, P = 0.037), while postoperative UDVA was a protective factor (OR = 0.036, P = 0.037) for overall QoV scores. Using binary logistic regression analysis, we found that patients with larger mesopic pupil size had an increased risk to experience glare postoperatively; compared to ICL, patients who underwent SMILE or FS-LASIK tended to report fewer halos; patients with better postoperative UDVA were less likely to report blurred vision and focusing difficulty; with larger residual myopic sphere postoperatively, patients experienced focusing difficulties and difficulty judging distance or depth perception more frequently.

CONCLUSIONS

SMILE, FS-LASIK, and ICL had comparable visual outcomes. Overall, glare, fluctuation in vision, and halos were the most frequently experienced visual symptoms 3 months postoperatively. Patients with ICL implanted tended to report halos more frequently compared with SMILE and FS-LASIK. Mesopic pupil size, postoperative UDVA, and postoperative residual myopic sphere were predicted factors for reported visual symptoms.

Managing Post-Keratoplasty Astigmatism: High-Tech vs. Low-Tech Imaging Techniques for Guiding Suture Manipulation

Astigmatism is a visually significant condition that can develop after keratoplasty. The management of post-keratoplasty astigmatism can be performed both when transplant sutures are in place and when they have been removed. Fundamental for astigmatism management is its identification and characterization in terms of type, amount, and direction. Commonly, post-keratoplasty astigmatism is evaluated through corneal tomography or topo-aberrometry; however, many other techniques can be used in case these instruments are not readily available. Here, we describe several low-tech and high-tech techniques used for post-keratoplasty astigmatism detection in order to quickly understand if it contributes to low vision quality and to determine its characteristics. The management of post-keratoplasty astigmatism through suture manipulation is also described.

Evaluating early-stage disk halo changes after small incision lenticule extraction

PURPOSE

To investigate early changes in the disk halo under different light conditions after myopic small incision lenticule extraction (SMILE).

METHODS

This prospective study included 70 eyes of 70 myopic patients aged 18-33 years, with a spherical equivalent (SE) of -5.87 ± 1.86 D, who underwent SMILE. The subjective refraction, higher-order aberrations (HOAs), pupillometry, and halo were measured preoperatively and postoperatively to analyse disk halo variations and correlated factors.

RESULTS

At 5 cd/m2 and 1 cd/m2 luminance, the halo radius in the high myopia (HM) group reached a postoperative peak after 1 week (p = 0.000 and 0.019, respectively), and recovered to baseline after 3 months. In the low-to-moderate (LM) myopia group, the halo radius did not differ 1 week postoperatively compared to the preoperative level (p = 0.015), but significantly improved after 3 months (p = 0.000). The halo radius correlated with SE, uncorrected distance visual acuity (UDVA), ocular HOAs, coma, and the pupillary light reflex in the LM group at all time points, but there were no correlations in the HM group.

CONCLUSIONS

Halo symptoms occurred early after SMILE, but recovered within 3 months. The recovery process was slower in the HM group than in the LM group, and the halo radius correlated with SE, UDVA, ocular HOAs, coma, and the pupillary light reflex.

The Effect of Age, Postoperative Refraction, and Pre- and Postoperative Pupil Size on Halo Size and Intensity in Eyes Implanted with a Trifocal or Extended Depth-of-Focus Lens

Purpose

Halos are a chief source of patient dissatisfaction after multifocal intraocular lens (IOL) implantation. The primary purpose of this study was to investigate the influence of age, postoperative refraction, and pre- and postoperative pupil size on postoperative halo size with a trifocal diffractive IOL (AcrySof IQ PanOptix) and extended depth-of-focus (EDOF) IOL (TECNIS Symfony) to determine whether these factors could predict postoperative halo size.

Patients and Methods

This single-center, open-label study conducted between October 2018 and April 2020 in Yokosuka, Japan included 160 patients: 80 with PanOptix and 80 with Symfony IOLs. Size and intensity of the halos were examined binocularly using a computer-based simulator (Eyeland Design Network GmbH) and scored from 0 (minimum) to 10 (maximum) at 1, 3, and 6 months postoperatively, along with the change in each variable for both IOLs. The respective correlations of halo size with age, postoperative refraction, pre- and postoperative pupil size, and discomfort level due to the halo were also investigated 6 months postoperatively.

Results

Halo size and intensity were significantly mitigated between 1, 3, and 6 months postoperatively. Throughout the observation period, halo size was significantly larger with PanOptix than with Symphony (P < 0.05), and halo intensity was significantly higher with Symphony than with PanOptix (P < 0.05). The pre- and postoperative pupil size correlated positively with halo size, while age and postoperative refraction were negatively correlated, for both IOLs.

Conclusion

Understanding the features and predictive preoperative factors of halos in different types of multifocal IOLs may be useful in improving patient satisfaction.

Comparative analysis of the clinical outcomes between wavefront-guided and conventional femtosecond LASIK in myopia and myopia astigmatism

AIM

To compare the clinical outcomes of wavefront guided femtosecond LASIK (WFG LASIK) and conventional femtosecond LASIK (NWFG LASIK) in eyes with myopia and myopia astigmatism.

METHODS

This was a retrospective, nonrandomized, comparative investigation enrolling 236 eyes of 122 patients (18-50y) with low & moderate and high myopia. The WFG group including 97 eyes (50 patients) undergone WFG LASIK and the NWFG group including 139 eyes (72 patients) undergone conventional LASIK. Mean efficacy index, high order aberrations (HOAs), pupil size and the quality of visual questionnaire were evaluated 6mo postoperatively.

RESULTS

There is no difference between WFG group (-0.054±0.049 in logMAR) and NWFG group (-0.040±0.056) in uncorrected distance visual acuity (UDVA) postoperatively. The myopia astigmatism is higher in WFG group than that in NWFG group (P<0.05). However, the mean efficacy index (MEI) in the WFG group (1.09±0.106) is better than that in the NWFG group (1.036±0.124; P<0.001). Increased HOAs were observed in NWFG group (0.30±0.196) than that in WFG group (0.146±0.188; P<0.001). The pupil size is larger in WFG group (5.15±0.76 mm) than that in NWFG group (4.32±0.52 mm). The patients are satisfied with the clinical surgery, yet WFG group showed better visual quality using the questionnaire survey. Meanwhile, high myopia would result in worse MEI, HOAs and visual quality than low & moderate myopia.

CONCLUSION

WFG and NWFG FS-LASIK are both effective and safe procedures to correct low & moderate and high myopia, but WFG FS-LASIK gives a better postoperative MEI, aberrometric control and predictable outcome. Meanwhile, WFG FS-LASIK is better than NWFG FS-LASIK in correction of myopia astigmatism. Low & moderate myopia allow better clinical outcomes than high myopia using any surgical method.

Customized eye modeling for optical quality assessment in myopic femto-LASIK surgery

Refractive surgery is recognized as an effective method for myopia treatment, but it can induce night vision disturbances such as glare. We present an eye modeling method for the optical quality assessment in response to the structural changes in the eyes by femto-LASIK surgery. Customized eye models were built from the measurements of 134 right eyes pre- and post-operatively. Optical performance was evaluated using spot diagrams, point spread functions (PSFs), modulation transfer functions (MTFs), and chromatic aberrations at various fields (0°-30°), different pupil diameters (2-6 mm), and initial myopias (- 1.25 to - 10.5 D). Pupil size and initial myopia are the two major factors that affect visual performance of post-operative eyes. The results of spot diagrams, PSFs, and MTFs indicated that post-operative visual performance deteriorated as the visual field and pupil size increased, and it was significantly influenced by initial myopia. Post-operative chromatic aberrations were also affected by initial myopia. As pupil size increased, the post-operative longitudinal chromatic aberrations tended to decrease slightly, while the transverse chromatic aberrations remained similar. The use of eye modeling for refractive surgery assessment could possibly provide a more personalized surgical approach, could improve the prediction accuracy of refractive surgery outcomes, and promote the invention and development of better surgical methods.

Complications of laser-assisted in situ keratomileusis

Laser-assisted in situ keratomileusis (LASIK) is one of the most commonly performed kerato-refractive surgery globally. Since its introduction in 1990, there has been a constant evolution in its technology to improve the visual outcome. The safety, efficacy, and predictability of LASIK are well known, but complications with this procedure, although rare, are not unknown. Literature review suggests that intraoperative complications include suction loss, free cap, flap tear, buttonhole flap, decentered ablation, central island, interface debris, femtosecond laser-related complications, and others. The postoperative complications include flap striae, flap dislocation, residual refractive error, diffuse lamellar keratitis, microbial keratitis, epithelial ingrowth, refractive regression, corneal ectasia, and others. This review aims to provide a comprehensive knowledge of risk factors, clinical features, and management protocol of all the reported complications of LASIK. This knowledge will help in prevention as well as early identification and timely intervention with the appropriate strategy for achieving optimal visual outcome even in the face of complications.

Effect of Wavefront Aberrations on Night Vision Problems and Mesopic Contrast Threshold After SMILE

PURPOSE

To investigate the effect of wavefront aberrations on night vision problems and mesopic contrast threshold after small incision lenticule extraction (SMILE).

METHODS

Forty-two participants (84 eyes) who underwent SMILE were included in this prospective observational study. Visual outcomes including uncorrected distance visual acuity (UDVA), subjective manifest refraction, mesopic contrast threshold (Binoptometer 4P; Oculus Optikgeräte GmbH), and higher order aberrations (HOAs) were analyzed before and 3 months after surgery. The patient's night vision satisfaction was assessed using a questionnaire.

RESULTS

The mean spherical equivalent was -5.30 ± 1.38 diopters (D) preoperatively and -0.06 ± 0.15 D postoperatively. UDVA was better than 20/20 in 98.81% of the patients and better than 20/25 in all patients. Scores of night vision satisfaction and glare changed significantly in the postoperative period (F = 8.463, P = .001; F = 69.518, P < .001, respectively). Preoperative spherical diopters (lower order aberrations) were positively correlated with night vision satisfaction (r = -0.329, P = .041) and glare score (r =-0.332, P = .039). Age (odds ratio [OR] = 1.272, 95% CI = 1.019 to 1.589) and preoperative spherical diopter (OR = 0.437, 95% CI = 0.199 to 0.975) were correlated with night vision satisfaction scores by analysis of binary regression. The root mean square value of total HOAs increased 3 months after surgery (t = -6.873, P < .001) with an increase in horizontal coma (Z₃¹) and spherical aberration (Z₄⁰) (P < .001). No correlation was observed between glare score and HOAs; however, patients with higher preoperative myopia demonstrated continuously decreasing contrast under mesopic conditions and higher postoperative horizontal coma.

CONCLUSIONS

Myopic patients with higher preoperative spherical errors experienced more glare at night after SMILE surgery. Postoperative horizontal coma was associated with worse mesopic contrast thresholds. [J Refract Surg. 2021;37(7):446-452.].

Effect of brimonidine tartrate 0.2% ophthalmic solution on visual quality after implantable collamer lens implantation with a central hole

PURPOSE

To investigate the effect of brimonidine tartrate 0.2% on visual quality after implantable collamer lens with a central hole (ICL V4c).

METHODS

This study comprised 59 consecutive patients implanted with an ICL V4c. Brimonidine was administered randomly into one eye of the patients with symptomatic glare or halos 1 week postoperatively and the contralateral eye with artificial tears as the control group. Visual quality (measured by a optical quality analysis system), pupil size and refraction under scotopic light conditions were measured before and 0.5, 1.5, 3 and 6 h after administration of brimonidine. A symptom questionnaire was also evaluated.

RESULTS

The visual quality improved and reached its maximum value, and the scotopic pupil size reached its minimum value 1.5 h after brimonidine administration, with a statistically significant difference seen from 0.5 to 3 h compared to baseline. No changes in refraction were seen after brimonidine. The questionnaire showed that symptoms of glare or halos could be eliminated after brimonidine in 58% of patients, be alleviated in 37% of patients and be unchanged in 5% of patient. However, 10% of patients experienced conjunctival congestion and some patients experienced reduced drug efficacy 1 month after treatment.

CONCLUSION

Brimonidine can be used to improve night visual quality in early postoperative period after ICL V4c implantation. It helps patients to quickly adapt to the glare or halos.

Effect of brimonidine tartrate 0.15% on scotopic pupil size and upper eyelid position: controlled trial

BACKGROUND

To evaluate the effect of brimonidine tartrate 0.15% ophthalmic solution on pupil size under scotopic condition and upper eyelid position.

METHODS

This study comprised 72 eyes of 36 healthy subjects. A single drop of brimonidine tartrate 0.15% ophthalmic solution was instilled in the right eye and artificial tear was instilled in the left eye. Pupil size was measured using an infra-red pupillometer under scotopic condition before and at 30 min, 2, 4, 6, 8 and 10 h after instillation. Measurement of margin reflex distance 1 (MRD1) was performed using a millimetre ruler before and after at 10 min after instillation.

RESULTS

The mean age of the subjects was 32.19 ± 11.43 years (range 10-52 years), 17 were female and 19 were male. Before brimonidine instillation, the mean pupil size was 6.09 ± 1.03 mm in the brimonidine eyes and 6.06 ± 1.04 mm in the control eyes. There was a significant decrease in mean pupil size at 30 min (4.45 ± 1.04), 2 h (4.49 ± 1.06), 4 h (4.59 ± 1.06), 6 h (4.89 ± 1.06) and 8 h (5.38 ± 1.02) after instillation compared to before in brimonidine eyes (p < 0.001 for all). There was a significant miosis continued for at least 6 h (5.95 ± 1.03) in control eyes (p < 0.001). There was no significant change in MRD1, before and after instillation both in brimonidine and control eyes.

CONCLUSIONS

Brimonidine tartrate 0.15% had a significant miosis under scotopic condition for at least 8 h after instillation and had a significant miosis on the untreated eye for at least 6 h.

Evaluation of disk halo size after small incision lenticule extraction (SMILE)

PURPOSE

To investigate changes in objective disk halo size produced by a glare source after small incision lenticule extraction (SMILE) for myopia correction.

METHODS

This prospective clinical study included 45 right eyes of 45 patients with a mean age of 25.40 ± 5.06 years and mean spherical equivalent (SE) of - 6.08 ± 1.90 diopters. Disk halo size was measured with a vision monitor before surgery and at postoperative 1 week and 3 months. Other information was collected, including age, SE, lenticule thickness, lenticule diameter, dark pupil, and pupillary response to light parameters (initial diameter; amplitude, latency, duration, and velocity of contraction; latency, duration, and velocity of dilation; and maximum, minimum, and average pupil size).

RESULTS

Compared to preoperative values, disk halo size increased significantly at postoperative 1 week (P = 0.026) and returned to baseline at postoperative 3 months (P = 0.349). Preoperative disk halo size significantly correlated with SE (r = - 0.346, P = 0.020), minimum pupil size (r = 0.365, P = 0.014), and average pupil size (r = 0.310, P = 0.038). Disk halo size at postoperative 1 week was significantly correlated with age (r = 0.324, P = 0.030) and minimum pupil size (r = 0.297, P = 0.047). Disk halo size at postoperative 3 months was significantly correlated with lenticule diameter (r = - 0.362, P = 0.015), initial diameter (r = 0.311, P = 0.037), maximum pupil size (r = 0.312, P = 0.037), minimum pupil size (r = 0.440, P = 0.002), and average pupil size (r = 0.373, P = 0.012).

CONCLUSIONS

After SMILE, disk halo size demonstrated a temporary increase and then returned to baseline.

Influence of refractive error on pupil diameters in highly myopic eyes with implantable collamer lenses

PURPOSE

To investigate the influence of refractive error on pupil diameters in highly myopic eyes with implantable collamer lenses.

SETTING

Shanghai, China.

DESIGN

A prospective consecutive observational study.

METHODS

Sixty-six eyes of 66 patients that underwent ICL V4c implantation were included. Pupil diameters before and 1 week, 1 month, and 3 months after surgery were measured using an automatic pupillometry system (MonCv3; Metrovision, Pérenchies, France) under four standardized illumination conditions: 0, 1, 10, and 100 cd/m². The correlations between changes in pupil diameter and spherical equivalent values and patient age were investigated.

RESULTS

Based on preoperative spherical equivalent values, included eyes were divided into a high-myopia group (-6.3 to -9.9 D (diopters)) and a super-high-myopia group (-10 to -20 D). Pupil sizes remained unchanged after surgery in the high-myopia group and decreased at 1 and 10 cd/m² in the super-high-myopia group. A between-group comparison showed that pupils were significantly smaller in the super-high-myopia group 1 week postoperatively under all illumination conditions and remained smaller at 1 month and 3 months under 1 and 10 cd/m² lighting conditions. Preoperative spherical equivalent values were significantly correlated with the percent decrease in pupil diameter 1 week postoperatively under 0, 1, and 10 cd/m² illumination conditions; the greater the degree of myopia, the greater the reduction in pupil diameter.

CONCLUSION

Preoperative refractive error significantly affects pupil diameter in highly myopic eyes after implantable collamer lens implantation. Pupils of super highly myopic eyes remained smaller than preoperative levels under mesopic conditions after implantable collamer lens implantation.

Visual outcomes and management after corneal refractive surgery: A review

Corneal refractive surgery procedures are widely performed to permanently correct refractive errors. Overall, refractive surgeries are safe, predictable and present high rates of satisfaction. Nevertheless, the induced epithelial, stromal and nerve damage alters corneal integrity and function, triggering a regenerative response. Complications that arise from corneal wound healing process might directly impact on visual outcomes of keratorefractive procedures. Most of these complications can be prevented or effectively treated with minimal consequences and minor impact on optical quality. Nevertheless, it is crucial to accurately and timely identify these corneal regeneration-related complications for successful counseling and management. Optometrists, as primary eye care providers, play an essential role in detecting anatomic and functional alterations in vision. It is therefore of great interest for optometrists to be familiar with the principal postoperative complications derived from alterations in regenerative process after corneal laser refractive surgeries. This review aims to provide a basis for optometrists to better understand, identify and manage the main wound healing-related complications after refractive surgery.

Q-optimized Algorithms: Theoretical Analysis of Factors Influencing Visual Quality After Myopic Corneal Refractive Surgery

PURPOSE

To model the effect of pupil size, optical zone, and initial myopic level on the retinal image quality after Q-optimized myopic corneal refractive surgery.

METHODS

Different Q-optimized and paraxial Munnerlyn algorithms were tested using a schematic myopic eye model to analyze the optical quality of the final retinal image for initial myopic errors from -1.00 to -7.00 diopters (D). Different optical zones (5.5, 6, and 6.5 mm in diameter) and two pupil diameters (5 and 7 mm, mesopic-scotopic conditions) were included in the comparison. Modulation transfer function (MTF) and area under the MTF from 0 to 60 cycles per degree (MTFa) were calculated by ray tracing to evaluate this retinal image quality.

RESULTS

The Q-optimized algorithm with Q = -0.45 provided the highest MTF and MTFa results for myopic corrections less than -5.00 D. For refractive errors greater than -5.00 D, Q = -0.26 provided the highest MTF and MTFa results.

CONCLUSIONS

Q-optimized algorithms improve the visual outcomes with respect to the paraxial Munnerlyn algorithm for myopic corneal surgery. The results show that the Q value that optimizes the results of the Q-optimized algorithm depends on the degree of myopia to correct and the size of the pupil. [J Refract Surg. 2016;32(9):612-617.].

[Visual improvement by aberration-free excimer laser retreatment : Therapy after combined photorefractive keratectomy and keratome laser in situ keratomileusis treatment]

A 23-year-old male patient presented with reduced visual acuity of the right eye, along with halos and starbursts in both eyes after a one-stage tissue-saving treatment, a combination of myopic photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). After an extensive preliminary examination and analysis of the examination results, aberration-free LASIK retreatment for reducing astigmatism and enlargement of the optical zone with an excimer laser was performed on the right eye. The visual performance and the subjectively perceived optical quality improved postoperatively.

Refractive Surgery: Malpractice Litigation Outcomes

PURPOSE

To review data on malpractice claims related to refractive surgery to identify common allegations and injuries and financial outcomes.

METHODS

The WestlawNext database was reviewed for all malpractice lawsuits/settlements related to refractive eye surgery. Data evaluated included patient demographics, type of operation performed, plaintiff allegation, nature of injury, and litigation outcomes.

RESULTS

A total of 167 cases met the inclusion criteria, of which 108 cases (64.7%) were found to be favorable and 59 cases (35.3%) unfavorable to the defendant. A total of 141 cases were tried by a jury with 108 cases (76.4%) favorable and 33 cases (23.6%) unfavorable to the defendant. Laser in situ keratomileusis was performed in 127 cases (76%). The most common allegations were negligence in treatment or surgery in 127 cases (76%) and lack of informed consent in 83 cases (49.7%). For all cases, the need for future surgery (P = 0.0001) and surgery resulting in keratoconus (P = 0.05) were more likely to favor the plaintiff. In jury verdict decisions, cases in which failure to diagnose a preoperative condition was alleged favored the defendant (P = 0.03), whereas machine malfunction (P = 0.05) favored the plaintiff. After adjustment for inflation, the overall mean award was $1,287,872. Jury verdicts and settlements led to mean awards of $1,604,801 and $826,883, respectively.

CONCLUSIONS

Malpractice litigation in refractive surgery tends to favor the defendant. However, large awards and settlements were given in cases that were favorable to the plaintiff. The need for future surgery and surgery leading to keratoconus increased the chance of an unfavorable outcome.

Single-step transepithelial photorefractive keratectomy in high myopia: qualitative and quantitative visual functions

AIM

To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy (TransPRK) in high myopia.

METHODS

In a prospective interventional case-series, 30 eyes with high myopia (-6.00 to -8.75 D) with (up to -3.00 D) or without astigmatism were enrolled from Bina Eye Hospital, Tehran, Iran. One-step TransPRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction, visual acuities, vector analysis, ocular wave-front (OWF) and corneal wave-front (CWF) higher order aberrations (HOA), contrast sensitivity (CS), and post-operative haze were assessed.

RESULTS

After the surgery, both photopic and mesopic CSs significantly improved (both P<0.001). We detected significant induction of OWF coma and trefoil (P<0.001 for both) HOAs; CWF coma (P=0.002), spherical (P<0.001), and tetrafoil (P=0.003) HOAs in 6 mm analysis diameter; and CWF trefoil (P=0.04) HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was 0.005-0.11 µm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis, mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation, no eye lost any number of corrected distance visual acuity lines. We detected no corneal haze greater than 1⁺ throughout the follow-up.

CONCLUSION

Our findings show promising effects of single-step TransPRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity.

Wavefront-guided versus wavefront-optimized photorefractive keratectomy: Clinical outcomes and patient satisfaction

PURPOSE

To compare visual outcomes following Visx Star S4 Customvue wavefront-guided and Allegretto Wave Eye-Q 400 Hz wavefront-optimized photorefractive keratectomy (PRK).

SETTING

Warfighter Refractive Eye Surgery Program and Research Center, Fort Belvoir, Virginia, and Walter Reed National Military Medical Center, Bethesda, Maryland, USA.

DESIGN

Prospective randomized clinical trial.

METHODS

Active-duty United States military soldiers were randomized to have wavefront-guided (Visx Star S4 Customvue) or wavefront-optimized PRK. Participants were followed up to 12 months postoperatively. Primary outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest spherical equivalent (SE). Secondary outcome measures included refractive astigmatism, higher-order aberrations (HOAs), contrast sensitivity, subjective visual complaints, and patient satisfaction.

RESULTS

The study evaluated 108 soldiers (mean age 30.3 years ± 6.3 [SD]; mean manifest SE -3.51 ± 1.63 D). At 12 months postoperatively, achieved UDVA, CDVA, manifest SE, and refractive astigmatism were comparable between wavefront-guided and wavefront-optimized groups (P > .213). Spherical aberration and total HOAs significantly increased from baseline in both groups (P < .006). The change in coma, trefoil, spherical aberration, and total HOAs (P > .254) were comparable between groups. There were fewer losses of photopic low-contrast visual acuity (LCVA) at 5% contrast after wavefront-guided compared to wavefront-optimized treatment (P = .003). There was no significant difference between treatment groups in visual symptoms, overall vision expectation, and satisfaction (P > .075).

CONCLUSION

Wavefront-guided treatment offered a small advantage in photopic LCVA. Refractive outcomes, HOAs, self-reported visual difficulties, overall vision expectation, and satisfaction were otherwise comparable between wavefront-guided and wavefront-optimized treatments.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Four-year visual outcomes after photorefractive keratectomy in pilots with low-moderate myopia

BACKGROUND

The photorefractive keratectomy (PRK) is approved for Air Force pilots in several nations. The occupational environments of pilots in the Air Force are unique, including extremely high altitude, low oxygen tension, high ultraviolet light exposure and high G-force load. The short-term efficacy and safety of PRK for pilots are documented. However, the study for long-term visual and refractive outcomes of PRK in pilots is limited.

OBJECTIVE

To investigate the long-term visual and refractive outcomes in a 4-year follow-up period after PRK in pilots with low to moderate myopia.

METHODS

Thirty-eight eyes of 20 subjects that underwent PRK and recruited to Air Force pilot were evaluated preoperatively and at 3, 6, 12, 24, and 48 months postoperatively.

RESULTS

The mean patient age was 21.42±0.75 years. The mean preoperative manifest refraction spherical equivalent (SE) was -1.51±1.15 diopters (D). At 4 years postoperatively, the mean SE was -0.29±0.51, 89.5% of eyes achieved 20/20 or better Snellen uncorrected visual acuity, 71.1% of eyes were within ±0.50 D of emmetropia. The refraction stabilised by 6 months and was maintained up to the 4-year follow-up stage.

CONCLUSIONS

PRK for pilots with low to moderate myopia is safe and effective in the long term. High-altitude environmental stress exposure has no effect on the refractive stability after PRK.

TRIAL REGISTRATION NUMBER

ROKAF-ASMC-2015-IRB-002.

A limitation of Hartmann-Shack system in measuring wavefront aberrations for patients received laser refractive surgery

Purpose

To explore the relationship between ablation parameters of myopic laser surgery and measurement area of wavefront aberration (WA) with Hartmann-Shack wavefront sensor.

Methods

58 subjects undergone myopic laser surgeries and 74 uncorrected myopic subjects were enrolled in this experiment. The laser ablation parameters were obtained from surgical records, which included spherical error (Rx), depth, and optical zone (OZ) of ablation. The measured area of WA was tested by the WASCA, and the real pupil size was tested by Pentacam. The corneal eccentricity (E value) and curvature was also measured with the Pentacam. All the measurements were performed under mydriatic condition.

Results

For uncorrected myopic eyes, the measured area of WA was similar with the real pupil size. But for the corrected eyes, the measured area of WA was smaller than the real pupil size with a mean difference of 0.66 ± 0.54 mm for moderate myopia (t = 6.45, p < 0.0001) and 1.76 ± 0.55 mm for high myopia (t = 18.92, p < 0.0001), but not for mild myopia. The Rx (t = -3.20, p = 0.0017), OZ (t = 64.4, p < 0.0001) and postoperative corneal E value (t = 2.52, p = 0.017) were the independent factors of measured area of WA. Measured area of WA = -0.81*Rx + 1.13*OZ + 0.49*postoperative corneal E value (r² = 0.997).

Conclusions

The WASCA has a limitation in measuring wavefront aberration over the whole pupil area when it’s used for patients received myopic laser surgery. The measured area is smaller than the real pupil size and depends linearly on ablation depth, optical zone and corneal eccentricity.

Pupil size and LASIK: a review

PURPOSE

To provide a literature review on the evidence both for and against pupil size as an independent predictor of adverse visual outcomes after LASIK.

METHODS

Peer-reviewed publications on the effect of pupil size on LASIK outcomes since 2002 are reviewed. Particular attention was paid to the following attributes of each publication: type of study, number of patients or eyes, mean age, mean level of myopia, mean pupil size, testing conditions, ablation zone diameter, presence or absence of blend zones, and mean follow-up period.

RESULTS

Among the 19 studies examined, none correlates a persistent relationship between pupil size and night vision complaints (NVCs) beyond 3 months when LASIK was performed with a 6.0-mm optical zone or larger ablation. The studies that did explicitly determine a correlation either included some or all patients with ablation zones smaller than 6.0 mm or did not specify ablation diameter at all. Among the studies that had drawn more mixed conclusions, the studies either covered short follow-up intervals (1 to 3 months) or showed a progressive improvement in NVCs over time in a relatively small patient cohort.

CONCLUSIONS

As keratorefractive technology continues to evolve, the role of pupil size warrants further investigation; however, based on the literature reviewed herein, modern LASIK has negated the role of the low light pupil in predicting adverse visual outcomes after LASIK outside of the early postoperative period.

Four-year visual, refractive, and contrast sensitivity outcomes after wavefront-guided myopic LASIK using an advanced excimer laser platform

PURPOSE

To evaluate the 4-year visual, refractive, and contrast sensitivity outcomes of wavefront-guided LASIK for the correction of low to moderate myopia using the VISX CustomVue technology (Abbott Medical Optics, Inc., Santa Ana, CA).

METHODS

This was a prospective study including 255 consecutive eyes of 145 patients (age range: 19 to 55 years) with low to moderate myopia (mean spherical equivalent: -3.36 ± 1.71 diopters [D]) undergoing laser refractive surgery. Wavefront-guided LASIK was performed in all eyes using the VISX STAR S4 IR excimer laser platform and the CustomVue procedure for the ablation profile design. Visual, refractive, and contrast sensitivity changes were evaluated during a 4-year follow-up period.

RESULTS

Postoperative logMAR uncorrected distance visual acuity was 0.1 or better (20/25 Snellen) in 98.0% and 100% of eyes at 1 and 4 years, respectively. At 4 years postoperatively, mean spherical equivalent was reduced significantly to a mean value of -0.22 ± 0.28 D (P < .01), with 97.3% of eyes with a spherical equivalent within ±0.50 D. The astigmatic power vector component J0 of manifest refraction was also reduced significantly (P < .01). Postoperative logMAR corrected distance visual acuity was 0.0 or better (20/20 Snellen) in 96.1% and 98.8% of eyes at 1 and 4 years, respectively. Improvement in contrast sensitivity was observed in some spatial frequencies between 1 and 4 years postoperatively. No significant correlations were found between 4-year contrast sensitivity and corrected distance visual acuity (0.024 ≤ r ≤ -0.120, P ≥ .06).

CONCLUSION

Wavefront-guided LASIK using the VISX CustomVue technology provides an effective and predictable correction of low to moderate myopia in the long term, preserving the patient's visual acuity and quality.

Small optical zones with aspheric profiles in laser refractive surgery for myopia: a surgical outcome and patient satisfaction study

PURPOSE

To assess the outcomes of small optical zone (OZ) ablations used in conjunction with large transition zones (TZ) and a highly aspheric treatment profile.

METHODS

Interventional case series of 39 consecutive patients with myopia or myopic astigmatism. Patient data included pre and postoperative refraction and visual acuities, laser treatment settings and pre and postoperative corneal topography as well as questionnaire responses about the use of glasses and the quality of vision postoperatively.

RESULTS

The mean preoperative spherical equivalent was -4.50±2.11 dioptres (D) and the mean OZ and TZ diameters were 4.5±0.5mm and 8.1±0.4mm, respectively. The mean patient age was 40.7±10.4 years. Manifest spherical refraction was within ±0.5D in 87% of patients (±1.0D in 99%) and cylindrical refraction within 0.5D in 79% (≤1.0D in 95%). The need to wear distance glasses postoperatively was associated with dissatisfaction with the quality of daytime vision (p=0.05) and unhappiness with night vision was associated with symptoms of halos (p=0.03) and starbursts (p=0.02). The proportion of patients reporting symptoms of dysphotopsias included: ghosting 0%; glare 2%; halos 10%; and starbursts 15%. There was a significant difference in the measured mean effective OZ diameter (4.8±0.3mm) compared to the mean programmed OZ (4.5±0.5mm, p=0.00).

CONCLUSIONS

Small ablation zones, when used in conjunction with a large diameter TZ, do not lead to a greater incidence of unwanted visual phenomena over that reported by many studies with larger OZs.

Visual outcomes of topography-guided excimer laser surgery for treatment of patients with irregular astigmatism

The aim of this study was to evaluate the efficacy, safety, and predictability of topography-guided treatments to enhance refractive status following other corneal surgical procedures. In a prospective case series study, 28 consecutive eyes of 26 patients with irregular astigmatism after radial keratotomy, corneal transplant, small hyperopic and myopic excimer laser optical zones, and corneal scars were operated. Laser-assisted in situ keratomileusis (LASIK) (n = 8) and photorefractive keratectomy (PRK) (n = 20) were performed using the ALLEGRETTO WAVE excimer laser and topography-guided customized ablation treatment software. Preoperative and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest and cycloplegic refraction, and corneal topography with asphericity were analyzed in 12 months follow-up. Uncorrected visual acuity (UCVA) changed from 0.2 ± 0.2 or (20/100 ± 20/100) to 0.51 ± 0.31 or (20/40 ± 20/60) in the LASIK group (P = 0.01) and from 0.34 ± 0.16 or (20/60 ± 20/120) to 0.5 ± 0.23 or (20/40 ± 20/80) in the PRK group (P = 0.01). Refractive cylinder decreased from -3.2 ± 0.84 diopters (D) to -2.06 ± 0.42 D in the LASIK group (P = 0.07) and from -2.25 ± 0.39 D to -1.5 ± 0.23 D in the PRK group (P = 0.008). Best corrected visual acuity did not change significantly in either group. Topography-guided treatment is effective in correcting the irregular astigmatism after refractive surgery. Topography-guided PRK can significantly reduce irregular astigmatism and increase the UCVA and BCVA.

Theoretical analysis of the effect of pupil size, initial myopic level, and optical zone on quality of vision after corneal refractive surgery

PURPOSE

To analyze the theoretical effect that pupil size, optical zone, and initial myopic level have on the final retinal image after corneal refractive surgery.

METHODS

A schematic myopic eye model corrected by the Munnerlyn formula was used to analyze the optical quality of the final retinal image. Root-mean-square radius spot and modulation transfer function were cal- culated by ray tracing to evaluate retinal image quality.

RESULTS

Pupil size had a negative effect on the retinal image only when it was greater than the diameter of the optical zone. In addition, the greater the initial myopic level, the more the pupil size affected image quality. Thus, a clear dependence exists between the initial myopic level and effect that the pupil size can have on the retinal image after laser refractive surgery.

CONCLUSIONS

Pupil size may be a risk factor for night vision disturbances, but only when it is larger than the theoretical optical zones utilized in this study. Its effect depends not only on the optical zone size, but also on the initial "myopic level. Therefore, this relationship should be taken into account during patient selection for refractive surgery

Mesopic pupil size in a refractive surgery population (13,959 eyes)

PURPOSE

To evaluate factors that may affect mesopic pupil size in refractive surgery candidates.

METHODS

Medical records of 13,959 eyes of 13,959 refractive surgery candidates were reviewed, and one eye per subject was selected randomly for statistical analysis. Detailed ophthalmological examination data were obtained from medical records. Preoperative measurements included uncorrected distance visual acuity, corrected distance visual acuity, manifest and cycloplegic refraction, topography, slit lamp examination, and funduscopy. Mesopic pupil size measurements were performed with Colvard pupillometer. Relationship between mesopic pupil size and age, gender, refractive state, average keratometry, and pachymetry (thinnest point) were analyzed by means of ANOVA (+ANCOVA) and multivariate regression analyses.

RESULTS

Overall mesopic pupil size was 6.45 ± 0.82 mm, and mean age was 36.07 years. Mesopic pupil size was 5.96 ± 0.8 mm in hyperopic astigmatism, 6.36 ± 0.83 mm in high astigmatism, and 6.51 ± 0.8 mm in myopic astigmatism. The difference in mesopic pupil size between all refractive subgroups was statistically significant (p < 0.001). Age revealed the strongest correlation (r = -0.405, p < 0.001) with mesopic pupil size. Spherical equivalent showed a moderate correlation (r = -0.136), whereas keratometry (r = -0.064) and pachymetry (r = -0.057) had a weak correlation with mesopic pupil size. No statistically significant difference in mesopic pupil size was noted regarding gender and ocular side. The sum of all analyzed factors (age, refractive state, keratometry, and pachymetry) can only predict the expected pupil size in <20% (R = 0.179, p < 0.001).

CONCLUSIONS

Our analysis confirmed that age and refractive state are determinative factors on mesopic pupil size. Average keratometry and minimal pachymetry exhibited a statistically significant, but clinically insignificant, impact on mesopic pupil size.

Corneal white-to-white distance and mesopic pupil diameter

AIM

To study the relationship between corneal white-to-white (WTW) distance and mesopic pupil diameter.

METHODS

This study is composed of 30 cases that underwent photorefractive keratotomy (PRK). Pupil size measurements were performed with Schwind ORK wavefront analyzer in mesopic conditions. WTW distance was measured with a measuring caliper. Also, A-scan ultrasound examination was performed in all patients. The relationship among the mesopic pupil diameter and age, sex, axial length, lens thickness, anterior chamber depth(ACD), horizontal WTW distance, vertical WTW distance, spherical equivalent, and average keratometry were analyzed with univariate and multivariate regression analysis.

RESULTS

Mean pupil diameter was (6.39±0.80)mm (range: 3.70mm-7.73mm). Horizontal WTW distance measurements were between 11.00mm and 12.50mm and mean horizontal WTW distance was (11.79±0.43)mm. On the other hand, vertical WTW distances ranged between 10.00mm and 13.00mm, and their mean was (11.42±0.72)mm. Bivariate correlation between pupil diameter and other variables showed that the axial length, ACD, spherical equivalent, and horizontal WTW distance had a moderate correlation with mesopic pupil diameter. Multiple regression analysis revealed that spherical equivalent and horizontal WTW distances were significantly associated with mesopic pupil diameter (R=0.598, R(2)=0.358 P=0.02).

CONCLUSION

This study shows that mesopic pupil diameter is closely related to horizontal WTW distance. These two factors must be taken in consideration together in preoperative ablation zone planning.

Comparison of 3 pupillometers for determining scotopic pupil diameter

PURPOSE

The pupil diameter under low ambient illumination is diagnostically valuable for refractive surgery. The aim of study was to compare the NeurOptics® Pupillometer, Sirius®, and Ocular Wavefront Analyser® in determining scotopic pupil diameter.

MATERIALS AND METHODS

A total of 96 eyes of 48 subjects were included. The scotopic pupil size was measured with 3 instruments and the measurements repeated following instillations of 1% cyclopentolate. Agreement between the instruments was assessed.

RESULTS

The mean measurement obtained by Sirius was significantly larger than Ocular Wavefront Analyser and NeurOptics. The Ocular Wavefront Analyser measured significantly smaller than the others. The mean cycloplegic pupillary diameters (7.73±0.70 mm with NeurOptics, 7.42±0.45 mm with Ocular Wavefront Analyser, and 8.06±0.76 mm with Sirius) were significantly different obtained by 3 instruments (p<0.001, for each; one-way analysis of variance and paired t tests).

CONCLUSIONS

The differences between measured pupil diameters with or without cycloplegia obtained by the NeurOptics, Sirius, and Ocular Wavefront Analyser were significant and have unacceptable levels of disagreement. These results may not be related to illumination and accommodation only, but also to measurement algorithms and technical differences of the devices.