Changes In Corneal Thickness Research Articles

Changes in Corneal Thickness Associated With Variation of Central Corneal Clearance of Scleral Lenses

Purpose: Modern scleral lenses (ScCLs) promote little tear exchange, limiting oxygen delivery to the cornea, possibly resulting in corneal edema. Recent studies have investigated the hypoxic effects of varying central corneal clearance (CCC) in short-term ScCL wear, and theoretical models have been proposed. The purpose of this study was to observe if there were hypothesized changes in corneal thickness associated with low levels of corneal hypoxia in healthy participants wearing ScCLs of different (CCC) over a longer term of wear.

Is central corneal thickness a constant during air puff indentation with Corvis ST?

AbstractPurposeCorvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) is the only commercial device that can capture corneal dynamic deformation in real time and provide a number of dynamic parameters, which include central corneal thickness (CCT). This study aimed to quantitatively analyse the change in CCT during air puff indentation using Corvis ST.MethodsSixty‐seven keratoconic eyes and 84 normal eyes were enrolled in this study. Dynamic videos were obtained from Corvis ST. An adaptive bilateral filtering method and a frame correlation method were used to remove noises. An adaptive threshold segmentation method was used to extract corneal boundary. The change in central corneal thickness, described as relative change rate of central corneal thickness (RCRCCT) and change speed of central corneal thickness (CSCCT) were compared between keratoconus group and normal cornea group.ResultsIt is shown that CCT would change and these two parameters were statistically significantly different between the keratoconus group and the normal cornea group RCRCCT, p = 0.014; CSCCT, p = 0.001.ConclusionsThe result of this study approved that CCT would change during air puff indentation. Further study is needed to develop more clinical applications based on these new findings, such as distinguishing keratoconus from normal cornea. image Fig. 1 Curves of changes in cornea and force over time. (A) Curve of corneal apex displacement and curve of air puff force; (B) A typical curve of the CCT changingover time. The red lineis the central corneal thickness‐time curve, the blue line is the force ‐time curve, and the green line is the fitting curveof force curve.

Evaluation of intraocular pressure and corneal thickness in individuals at high altitude area (10000 ft above sea level)

Background. At high altitude changes in corneal thickness and intraocular pressure (IOP) has been a subject of investigation for decades. The mechanism of action of these changes is still unknown. Extensive research is carried out to know effect of hypoxia on humans at high altitude. Corneal thickness and intraocular pressure are important parameter in ophthalmology with both diagnostic and therapeutic implications. We studied the corneal thickness and intraocular pressure in highlanders and compared the same with lowlanders. Methods. This observational study included two groups, each consisting of 500 individuals residing at high altitude (more than 10,000 ft above sea level). Three measurements of intraocular pressure of both eyes in each group were noted with Goldmann applanation tonometer and mean of the three readings was taken. Central Corneal Thickness (CCT) was measured by ultra sound pachymetry. The parameters of two groups were compared statistically. Results. There was a statistically significant difference between corneal thicknesses of the two groups studied, however no overall statistically significant difference in intraocular pressure of both these groups was found. Conclusion. The highlanders have a thinner cornea as compared to lowlanders. The IOP is significantly higher in the highlander males as compared to lowlander males. However, the mean IOP is comparable between the overall population of the high altitude and that of low altitude.

Finite element simulation of Goldmann tonometry after refractive surgery

BackgroundThe problem of accuracy of intraocular pressure (IOP) measurement using Goldmann Applanation Tonometry (GAT) after a refractive surgery is still unresolved.In this study a numerical simulation of refractive surgery and GAT is proposed as a method to evaluate accuracy of the correction formula for GAT reading after changes in corneal curvature and thickness. MethodsIn the finite element analysis the effect of the corneal shell buckling was taken into account. This effect is responsible for the nonlinear relation of Goldmann applanation tonometer measurement and intraocular pressure. Goldmann applanation tonometry was simulated for different ablation depths and values of intraocular pressure levels. FindingsThe results of the simulation indicate a strong relation between the Goldmann applanation reading and the intraocular pressure level for values greater than nominal (about 16 mmHg). The estimation error of the intraocular pressure after changes in corneal geometry, is lower than 1 mmHg for IOP = 32 mmHg and lower than 3 mmHg for IOP = 48 mmHg. InterpretationThe proposed correction formula of Goldmann applanation tonometry occurred to be useful in the cases after the corneal refractive surgery regardless of the intraocular pressure values and ablation depth.

Corneal Cross-linking in Thin Corneas: 1-Year Results of Accelerated Contact Lens-Assisted Treatment of Keratoconus.

To evaluate the safety and efficacy of accelerated contact lens-assisted cross-linking (A-CACXL) for patients with keratoconus and thin corneas. This retrospective study included consecutive patients undergoing A-CACXL for progressive keratoconus from 2015 to 2017. Patients with a minimum corneal thickness of 400 µm or less after epithelium removal who underwent A-CACXL (9 mW/cm2 for 10 minutes, using iso-osmolar 0.1% riboflavin solution and a 90-µm thick, daily disposable bandage soft contact lens) with a follow-up time of 12 months or more were included. The main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuity and minimum corneal thickness at the last visit. Progression (increase) and flattening (decrease) were defined as a change of 1.00 diopters (D) or greater in maximum keratometry or 1.50 D or greater in mean keratometry. Overall, 24 eyes of 24 patients were included with a follow-up time of 18.2 ± 6.3 months and a mean minimum corneal thickness, after epithelial debridement, of 353.13 µm. There was a significant improvement in UDVA (P = .009), maximum keratometry (P = .03), anterior steep keratometry (P = .04), anterior astigmatism (P = .02), and posterior astigmatism (P = .04) with no significant change in minimum corneal thickness (P = .11). There was a significant improvement in UDVA (0.90 ± 0.63 to 0.64 ± 0.47 logMAR, P = .009), maximum keratometry (61.20 ± 6.30 to 59.90 ± 5.70 D, P = .03), anterior steep keratometry (55.10 ± 3.90 to 54.50 ± 4.10 D, P = .04), anterior astigmatism (5.50 ± 2.40 to 4.60 ± 2.10 D, P = .02), and posterior astigmatism (0.90 ± 0.40 to 0.80 ± 0.40 D, P = .04) with no significant change in minimum corneal thickness (from 399.8 ± 30.7 to 391.0 ± 43.8 μm, P = .11). Flattening occurred in 45.8% (n = 11) and progression in 20.8% (n = 5). There were no serious adverse events. Persistent clinically significant stromal haze occurred in one case and completely resolved by 6 months. There was no significant change in endothelial cell density (P = .10). In patients with keratoconus and thin corneas, A-CACXL halted keratoconus progression in 80%, led to flattening in 45%, and significantly improved UDVA and keratometry values without any evidence of damage to the corneal endothelium or permanent adverse events. [J Refract Surg. 2019;35(10):642-648.].

Changes in Endothelial Specular Microscopy findings before and after Corneal Cross-linking

Purpose : The purpose of our study is to assess safety of CXL with epithelium removal for the treatment of KC on the corneal endothelium by using endothelial specular microscopy comparing the following parameters (cct , cv, cd, hex) before and after CXL.Patients and methods: This study was performed in Sohag ophthalmology department in Sohag university hospital in collaboration with Sohag Oyon misr centre. A total of 30 keratoconic eyes of 23 patients were evaluated for corneal thickness and endothelial cell changes before and 6 monthes after CXL (with specular microscopy).Results:Mean age of the study group was 28.70 years ± 3.5 years ranged from (22-33) years old .There was no significant difference between pre-and postoperative CCT or CD but CV increased and HEX decrease signsificantly.Conclusion: Epi-off CXL method has been firmly established to be safe on corneal endothelium , effective and the global standard of care for the treatment of progressive keratoconus.

A multimodal ophthalmic analysis in patients with systemic sclerosis using ocular response analyzer, corneal topography and specular microscopy

To conduct a multimodal ophthalmic evaluation of systemic sclerosis (SSc) in patients using ocular response analyzer (ORA), Pentacam, and specular microscopy (SM). Thirty-one SSc patients and a group of age- and sex-matched controls were enrolled in this cross-sectional study. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc), and Goldmann-correlated IOP (IOPg) were measured with ORA. Anterior chamber depth (ACD), central corneal thickness (CCT), and corneal volume (CV) measurements were obtained using Pentacam. Corneal endothelial cell density (ECD) and CCT were evaluated by SM. SSc patients had significantly lower CH, ACD, and ECD values compared to the control group (p = 0.018; < 0.001; < 0.001, respectively). There was no significant difference regarding CRF, IOP, CV, or CCT measurements acquired by Pentacam and SM. Regarding CCT, SM and Pentacam showed relatively better agreement in SSc patients. Multimodal imaging can provide more comprehensive and useful information regarding the ocular involvement of systemic diseases. The multimodal evaluation in our study demonstrated that the pathologic effects of SSc may manifest as reductions in ACD, corneal elasticity, and ECD before there are any detectable changes in corneal thickness or IOP.

Phacoemulsification vs Manual Small Incision Cataract surgery in eyes affected by pseudo exfoliation syndrome with grade II and III Cataracts

PurposeTo compare the postoperative alteration of central corneal thickness (CCT) and visual outcomes between phacoemulsification (group A) and manual small incision cataract surgery (MSICS) (group B) in grade II and III nuclear cataracts (NS II & III) with pseudoexfoliation syndrome (PXF). MethodsIt is a double masked prospective randomised interventional study. A total of 60 eyes of 60 patients were assigned randomly to either the phacoemulsification (group A) or MSICS (group B) groups. All eyes had nuclear sclerosis grade II and III (LOCS II grading system) with pseudoexfoliation material either over the pupillary margin, anterior lens capsule, or both. All surgeries were done by a single surgeon. Postoperative evaluation was scheduled on the 1st, 30th, 90th, and 180th-day. Statistical analyses were done using appropriate methods. Outcome of the study were measured with changes in central corneal thickness (CCT), Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA) and the spherical equivalent in the operated eye up to 6 months post surgery. ResultsThe mean preoperative CCT showed no difference between the groups (0.9659). The mean rise in CCT on the 1st postoperative day (POD) showed a significant difference between the groups {24.65 (SD 9.32) [group A (Phacoemulsification)] and 33.34 (SD11.68) [group B (MSICS)] (p < 0.0023)}. At the 1st, 3rd, and 6th month postoperative visits, there was no significant difference. The mean uncorrected distance visual acuity (UDVA) on the 1st POD was 0.189 (SD 0.118) in Group A and 0.302 (SD 0.121) in group B (p < 0.0005) which was significantly better with the phacoemulsification procedure. At the 1st month it was 0.039 (SD 0.084) in group A and 0.148 (SD 0.089) in group B (p < 0.004), which remained almost stable after that. The mean corrected distance visual acuity (CDVA) at the 1st, 3rd, and 6th-month postoperative visits showed no significant difference (p 0.8). The mean spherical equivalent was 0.29 in group A and 0.8 in group B. ConclusionIn moderately hard nuclear cataracts with PXF, phacoemulsification provides better unaided visual outcomes with less endothelial dysfunction than MSICS in the immediate and subsequent postoperative period.

Corneal Endothelial Morphology and Thickness Changes in Patients with Gout

Objectives:To investigate corneal endothelial cell density (ECD), morphology, and central corneal thickness (CCT) in patients with gout compared with healthy subjects.Materials and Methods:Fifty eyes of 50 gout patients and 50 eyes of 50 healthy subjects without gout or any other systemic disease were included in this study. After detailed ophthalmologic examination, specular microscopy (Tomey EM-4000; Tomey Corp) measurement was performed for all participants. ECD, average cell area (ACA), coefficient of variation (CV), hexagonality ratio, and CCT values were recorded.Results:Mean ECD and hexagonality ratio were lower (p=0.004 and p=0.002) and CV, ACA, and CCT values were higher (p=0.001, p=0.007, and p=0.001) in patients with gout when compared to healthy subjects. There were significant correlations between gout disease duration and CD and hexagonality ratio (p=0.019 and p=0.043) and also between uric acid value and hexagonality ratio and CCT (p=0.044 and p=0.003).Conclusion:Altered corneal endothelial function was found in patients with gout when compared to healthy subjects and the alteration increased as gout duration and uric acid value increased.

Topographic Study of Corneal Periphery in Selected Rheumatic Diseases

Background: many of autoimmune diseases associated with ophthalmological complication, such as Peripheral ulcerative keratitis. Objective: to evaluate the potential changes in the peripheral corneal thickness in selected rheumatic autoimmune diseases. Patients and Methods: a case control study was been held in Al-Azhar University Hospitals on 80 eyes for 40 patients and subjects. The patients and subjects was been examined by Pentacam examination. Results: as regard peripheral corneal thickness, the mean peripheral thickness of RA patients was 668.6 ± 32.1 micron, the mean peripheral thickness of SLE patients was 667.5 ± 34.8 micron, the mean peripheral thickness of SNA patients was 637.8 ± 86.7 micron and the mean peripheral thickness of control patients was 681.2 ± 12.8 micron (p-value = 0.045). Conclusion: the peripheral corneal thickness was thinner in autoimmune patients than in normal subjects.

Topographic Study of Corneal Periphery in Selected Rheumatic Diseases

Background: many of autoimmune diseases associated with ophthalmological complication, such as Peripheral ulcerative keratitis. Objective: to evaluate the potential changes in the peripheral corneal thickness in selected rheumatic autoimmune diseases. Patients and Methods: a case control study was been held in Al-Azhar University Hospitals on 80 eyes for 40 patients and subjects. The patients and subjects was been examined by Pentacam examination. Results: as regard peripheral corneal thickness, the mean peripheral thickness of RA patients was 668.6 ± 32.1 micron, the mean peripheral thickness of SLE patients was 667.5 ± 34.8 micron, the mean peripheral thickness of SNA patients was 637.8 ± 86.7 micron and the mean peripheral thickness of control patients was 681.2 ± 12.8 micron (p-value = 0.045). Conclusion: the peripheral corneal thickness was thinner in autoimmune patients than in normal subjects.

A study on changes in the central corneal thickness among pregnant mothers in south India

Introduction: Changes in every organ system during pregnancy is noted, even though pregnancy is said to be physiological. The changes can be physiological or pathological. The physiology of pregnancy is a curious issue for specialists from different branches of medicine. Our study was done to know the changes in the central corneal thickness during un complicated pregnancy. Aim and Objectives: The aim is to study the changes in the central corneal thickness during pregnancy. Materials and Methods: 80 eyes from 40 pregnant females with no other systemic or pregnancy related comorbidities were examined and the central corneal thickness was measured. Ultrasonic contact pachymetry was used to find out the central corneal thickness. Results: An increase in the central corneal thickness was found among the study population which was statistically significant. Very thick cornea more than 600 microns, was found in mothers in third trimester of pregnancy. Conclusions: The changes during pregnancy that are physiological in eyes are usually asymptomatic and transient. This change is only because of the hormonal influence and hence is expected to return to normal after delivery. But, the knowledge on these changes will help the patient when needed. Central corneal thickness was found to be increased in 62 eyes in this study population. Keywords: Central corneal thickness, Hormonal influence, Pregnancy, Pachymetry.

A study on changes in the central corneal thickness among pregnant mothers in south India

A study on changes in the central corneal thickness among pregnant mothers in south India

Application of optical coherence tomography and optical path length method for monitoring corneal thickness and refractive index change during corneal cross-linking.

Corneal cross-linking (CXL) using UVA irradiation with a riboflavin photosensitizer has emerged as a new treatment paradigm for corneal ectatic disorders. The thickness threshold for protection of intraocular structures has often been challenged with ongoing developments, and corneal thinning becomes an important safety concern, especially for patients with thin corneas. In this study with an ex vivo bovine eye model, we monitored corneal thinning and corneal refractive index changes using optical coherence tomography (OCT) integrated with an adaptation of the optical path length method. CXL experiments were performed based on the standard protocol that includes removal of the corneal epithelium to facilitate diffusion of riboflavin into the stroma. The corneal stromal thickness and group refractive index were measured by a 1310nm Fourier-domain OCT imaging system at three critical points of the procedure: immediately after epithelial removal, after 30min riboflavin instillation, and after 30min UVA irradiation with continuing instillation. We found that the refractive index of the bovine cornea changed significantly from epithelial removal to riboflavin instillation and UVA irradiation, increasing from 1.377±0.005 (mean±standard deviation) after de-epithelization to 1.387±0.003 after 30min instillation and 1.388±0.008 after subsequent irradiation. The corneas also underwent a considerable decrease (10%-20%) in stromal thickness with thinning of 95±29 μm (mean±standard deviation) after riboflavin instillation and a further decrease (∼5%) with thinning of 42±19 μm after UVA irradiation. Our study highlights the importance of corneal thickness monitoring during CXL, especially after riboflavin instillation when the decrease is the largest, to avoid delivering endothelial cytotoxic doses. An increase in refractive index heightens the concern for corneal thinning and the need for careful monitoring as a safety precaution.

Effect of the variability in implantation depth of intracorneal ring segments using the femtosecond laser technology in corneal ectasia.

To analyze the impact of the depth of implantation of intracorneal ring segments on morphological, biomechanical, and clinical outcomes in ectatic corneas. This prospective longitudinal study enrolled 40 eyes of 29 patients (age 20-51 years) with corneal ectasia that underwent intracorneal ring segments implantation (KeraRing, Mediphacos). Changes in visual acuity, refraction, corneal tomography, and corneal biomechanics (Ocular Response Analyzer, Reichert) were evaluated during a 6 month follow-up. Likewise, changes in ring segment implantation depth measured by optical coherence tomography (Visante OCT, Carl Zeiss Meditec) were also evaluated. Mean relative depth of implantation was 71.6 ± 5.8%, 71.5 ± 6.5%, and 71.9 ± 6.3% at 1, 3, and 6 months after surgery, respectively (p = 0.827). The difference between the real relative depth of implantation and the theoretical attempted value of 70% was not statistically significant (p = 0.072). Differences in spherical equivalent during the follow-up changed significantly depending on the level of relative depth of implantation (p = 0.036), with an increase of 0.114 D per each 1% increase in relative depth of implantation. Likewise, a decrease of -0.194 D in the steepest keratometric reading was found per each decrease of 1% in relative depth of implantation (p = 0.026). Changes in corneal thickness (p = 0.092) and biomechanics (p = 0.080) were not related to relative depth of implantation. The effect on visual acuity and refraction of intracorneal ring segments when implanted in corneal ectasia is less clinically relevant when the implantation is done at a very deep plane. The variability of the depth of intracorneal ring segments implantation when using femtosecond laser technology is minimal and with no clinically significant effect on clinical outcomes.

Comparison of changes in corneal endothelial cell density and central corneal thickness between conventional and femtosecond laser-assisted cataract surgery: a randomised, controlled clinical trial

Background/AimTo identify changes in endothelial cell density (ECD) and central corneal thickness (CCT) in eyes undergoing femtosecond laser-assisted cataract surgery (FLACS) compared with conventional phacoemulsification surgery (CPS).MethodsThis is an intraindividual...

Corneal thickness and endothelial changes in long-term hydroxychloroquine use

Objective: To determine possible associations between long-term HCQ use and corneal changes in patients who used HCQ for at least 3 years.Materials and methods: The study included 62 healthy controls and 62 consecutive patients who used HCQ for the treatment of rheumatologic disease and were referred to the ophthalmology department between August 2018 and November 2018 for HCQ retinal toxicity screening. Central corneal thickness (CCT), corneal endothelial cell density (ECD), the coefficient of variation (CV) of cell size, and the percentage of hexagonal cells (HEX%) were measured to evaluate changes in the cornea.Results: The mean age of the patient group and control group was 50.10 ± 10.91 and 50.53 ± 10.67 years, respectively. The mean ECD was 2742 ± 347 (cells/mm2) in the patient group and 2875 ± 188 cells/mm2 in the control group. There was a significant difference between groups (p = 0.01). The mean CCT was 567.05 ± 32.35 µm in the patient group and 540.15 ± 38.50 µm in the control group. CCT was significantly higher in the patient group compared with control group (p < 0.001). There was no significant difference between groups in terms of mean CV and HEX values (p > 0.05).Conclusions: Patients using long-term HCQ demonstrated lower ECD and higher CCT than the control group. However, the CV of cell sizes and the HEX % values were not significantly different from the controls.

Torsional and burst mode phacoemulsification for patients with hard nuclear cataract: A randomized control study.

This article aims to evaluate the outcomes of torsional and burst mode phacoemulsification in hard nuclear cataracts.Eighty eyes with grade IV or V nuclear opalescence were treated with phacoemulsification and intraocular lens implantation using conventional mode (Group A, n = 40) or torsional and burst mode phacoemulsification (Group B, n = 40). For good visualization of anterior capsule, trypan blue was injected to the anterior chamber before continuous circular capsulorhexis. The mean cumulative dissipated energy and ultrasound time were recorded. The best-corrected visual acuity, endothelial cell density, and central corneal thickness were measured before and at 1 month after surgery.The cumulative dissipated energy and ultrasound time of Group B were significantly less than that of Group A. The postoperative best-corrected visual acuities of the 2 groups were comparable. At 1 month after surgery, the changes in the endothelial cell density were significantly greater in Group A than in Group B, and the changes in the central corneal thickness were not significantly different between the 2 groups.Torsional and burst mode is a safe and effective surgical method for treating hard cataracts.

Effect of Riboflavin Solution With Hydroxypropyl Methylcellulose and Eyelid Speculum on Pachymetry Changes During Accelerated Collagen Crosslinking.

To assess corneal thickness changes with isotonic riboflavin (RF) solution with hydroxylpropyl methylcellulose in patients undergoing accelerated corneal collagen crosslinking (CXL) with and without an eyelid speculum. Fifty-two eyes of 48 patients with progressive keratoconus were enrolled in this study. The patients in this study were divided into 2 groups: in group 1 an eyelid speculum was removed during 20-minute RF (0.1%) + hydroxylpropyl methylcellulose (Mediocross M; Avedro Inc, Waltham, MA) instillation, and in group 2 the eyelid speculum was retained in place during the entire CXL procedure. All patients underwent accelerated CXL using continuous ultraviolet-A (UVA) light exposure at 9 mW/cm for 10 minutes; total energy dose was 5.4 J/cm. Intraoperative ultrasound pachymetry measurements were obtained before and after epithelial removal, after RF loading, and after UVA light exposure at 5 and 10 minutes. The preoperative pachymetric measurements decreased in both groups after the removal of epithelium [group 1 (n = 26): -25 μm, group 2 (n = 26): -31 μm, P = 0.234]. Although the thinnest pachymetry significantly increased after soaking in both group 1 (52.26 μm) and group 2 (27.88 μm, P < 0.001), closure of the eyelids during RF instillation further increased the pachymetry readings (P < 0.0001). The corneal thickness remained stable in both groups during UVA irradiation at 5 and 10 minutes (P > 0.05). Closure of the eyelids further induces corneal swelling that may offer an advantage to improve safety of the procedure particularly in thin corneas.

Central corneal thickness changes following manual small incision cataract surgery versus phacoemulsification for white cataract

Aim: To assess the central corneal thickness (CCT) and endothelial cell loss after manual small-incision cataract surgery and phacoemulsification in patients with white cataract. Material and methods: This is a comparative, prospective, non-randomized study on 42 patients with white cataract, who underwent cataract surgery. The patients were divided into manual small-incision cataract surgery (21 eyes, MSICS group) and phacoemulsification cataract surgery group (21 eyes, phaco group). The endothelial cell density (ECD), central cornea thickness (CCT), and corrected distance visual acuity (CDVA) were evaluated at 1 day, 1 week, 4 weeks, and 3 months postoperatively. The results of 20 cases of nuclear sclerosis grade II-III (LOCS III) who underwent phacoemulsification by the same surgeon were also compared. Propensity scoring was used to adjust for confounding by selection bias. Results: The CCT increased after surgery in both groups. The thickness was greater in the phaco group on first day postoperatively (73 µ increase in MSICS group and 138 µ in phaco group, p=0.008) and it returned to preoperative levels 1 month postoperatively. The endothelial cell loss was lower in the MSICS group at 3 months postoperatively (11.8% in MSICS group and 15.8% in phaco group, p=0.111). The CDVA was not different in both groups at 1 week and 4 weeks postoperatively (p>0.05). Conclusions: Manual small-incision cataract surgery for white cataract provided less central corneal thickness changes compared to conventional phacoemulsification. Abbreviations: CCT = central corneal thickness; ECD = endothelial cell density; CDVA = corrected distance visual acuity; APT = absolute phacoemulsification time; EPT = effective phacoemulsification time; MSICS = Manual small-incision cataract surgery in white cataract; Phaco II = Phacoemulsification in white cataract; Phaco I = phacoemulsification in NS 2 + Cataract; Phaco = Phacoemulsification in white cataract; APACRS = Asia-Pacific Association of Cataract and Refractive Surgeons.