Spherical Refractive Power Research Articles

Epithelial Remodeling and Epithelial Wavefront Aberrometry after Spherical vs. Cylindrical Myopic Small Incision Lenticule Extraction (SMILE).

Background/Objectives: To compare the epithelial thickness changes and the changes in epithelial wavefront aberrometry following spherical versus astigmatic myopic small incision lenticule extraction (SMILE). Methods: Eighty-six eyes of 86 patients who underwent SMILE were included in this retrospective study. A total of 43 eyes underwent myopic spherical correction (spherical group) and 43 eyes underwent myopic cylindrical correction (cylindrical group). The groups were matched according to the spherical equivalent of surgically corrected refraction. Subjective manifest refraction as well as high-resolution anterior segment optical coherence tomography (MS-39; CSO; Florence, Italy) were obtained preoperatively as well as 3 months postoperatively. The latter was utilized for computing epithelial wavefront aberrometry in addition to epithelial thickness mapping. Results: Epithelial thickness increased significantly in both groups after SMILE (p < 0.01). In the cylindrical group, epithelial thickening was more pronounced on the flat meridian compared to the steep meridian (p = 0.04). In both groups, epithelial wavefront aberrometry showed a significant postoperative increase in the epithelium's spherical refractive power, causing a myopization of -0.24 ± 0.42 diopters (D) in the spherical group (p < 0.01) and -0.41 ± 0.52 D in the cylindrical group (p < 0.0001). While no significant changes in epithelial cylindrical refractive power were observed in the spherical group, a significant increase was noted in the cylindrical group from -0.21 ± 0.24 D to -0.37 ± 0.31 D (p = 0.01). In both groups, epithelial higher-order aberrations increased significantly (p < 0.001). Conclusions: Postoperative epithelial remodeling after SMILE alters lower-order (sphere and cylinder) and higher-order aberrations of the corneal epithelial wavefront and might contribute to refractive undercorrection, especially in astigmatic corrections. Epithelial wavefront aberrometry can be used to quantify the refractive effect of epithelial remodeling processes after keratorefractive surgery.

Determination of depression, anxiety, and hopelessness levels in adolescents with refractive errors after the COVID-19 pandemic

Background/Aim: The prevalence of myopia is increasing worldwide especially among adolescents. Changes in living conditions such as reduced engagement in outdoor activities as well as increased activities near the workplace like reading, writing, and screen exposure are thought to be responsible for this increase. Adolescence is a sensitive period of rapid changes in psychological, physiological, and social aspects. Mental health issues such as anxiety and depression are common during this period. During the pandemic, mental health issues among children and adolescents increased due to stress caused by the disease, social isolation, disruption of routines, and the loss of loved ones. With the rapid increase in myopia among adolescents, there is a need to investigate the effects of myopia on mental health. The aim of this study is to evaluate anxiety, depression, and hopelessness levels in adolescents with myopia after the COVID-19 pandemic and to examine the relationship between myopia and anxiety, depression, and hopelessness. Methods: This was a case-control study that included 40 myopic adolescents aged 16-19 with a spherical refractive degree of -2 diopters (D) and above and 40 emmetropic (no refractive error). Participants who had previously undergone refractive surgery, had binocular visual acuity less than 1.0, had strabismus and amblyopia, had a diagnosis of glaucoma, had undergone ocular surgery for any reason, had retinopathy, or had an astigmatic refractive degree greater than ±0.50 were excluded from the study. The study did not include patients with chronic physiological or psychiatric diseases. Both groups were administered the Automatic Thoughts Questionnaire (ATQ), Coronavirus Anxiety Scale (CAS), Beck Hopelessness Scale (BHS), and Beck Depression Inventory (BDI). The groups were compared according to the scales. Myopic degrees were compared with mixed-effect linear models according to scale categories, and the relationship between ATS scores and myopia degrees was evaluated using the Spearman correlation coefficient. Results: The mean (SD) spherical refractive power of myopic adolescents was -3.156 (1.40) diopters; 62.5% of participants with myopia had been exposed to COVID-19, and the anxiety rate in myopic participants compared to controls was 15% (P=0.026). However, no significant difference was found between the myopia and control groups in terms of automatic thoughts, hopelessness, and depression inventory scores when comparing the groups. No correlation was found between the CAS (F=1.098), BHS (F=1.610), BDI (F=1.699), and ATQ (r=0.151) scales and the increase in myopia when we performed linear mixed model analysis and Spearman correlation analysis. There was no significant relationship between the degree of myopia and automatic thoughts, hopelessness anxiety, and depression. Conclusion: The results indicate that adolescents with myopia had higher levels of anxiety after the COVID-19 pandemic. There was no significant correlation between the degree of myopia and anxiety, depression, hopelessness, and automatic thoughts. It is important to monitor adolescents with myopia carefully during pandemics and provide the necessary mental health support. This is because offering mental health support to myopic young people may protect them from potential lasting emotional problems in adulthood during potential future pandemics. It may be beneficial for adolescents to increase their engagement in outdoor activities to reduce myopia and anxiety.

Effects of General Anesthesia on Ocular Refraction

ABSTRACT Purpose General anesthesia alters the autonomic nervous system. This study aimed to investigate the effects of general anesthesia on objective ocular refraction. Methods A total of 57 patients (112 eyes) under 15 years of age who underwent strabismus surgery under general anesthesia were included in this study. Objective refraction values, corneal refraction values, and pupil diameter were measured using a HandyRef-K, a hand-held refractive keratometer, in the operating room before and during general anesthesia before strabismus surgery. Results The spherical power of the myopic eye increased from −0.75 D to −2.29 D (diopter); the cylindrical power increased from −0.90 D to −1.39 D (p < .01 for all). The corneal refractive power decreased by an average of 0.25 D (p < .01). The spherical refractive power was negatively correlated with the age and the amount of change between cycloplegia before general anesthesia and during general anesthesia (r = −0.32, p < .05). Conclusions General anesthesia resulted in manifestation of myopia as noted by the objective refraction values. Corneal refractive values flatten under the same conditions, suggesting that the contraction of the ciliary muscles was the main cause of myopia. We speculate that this change was due to parasympathetic dominance and contraction of the ciliary muscles during general anesthesia.

The Association between Serum 25-hydroxyvitamin D Level and Myopia in Korean

Purpose : The purpose of this study was to investigate the relationship between serum 25 (OH) vitamin D level and myopia in Korean. Methods : Using data from the National Health and Nutrition Survey 2010, a total of 5,488 people aged 10 to 69 were targeted. Myopia was divided into subcategories as follows: mild myopia (-3.00<SE≤-0.50 D), moderate myopia (-6.00<SE≤-3.00 D), and high myopia (SE≤-6.00 D). Serum 25 (OH) vitamin D concentration was classified into two types as follows: deficiency (<20 ng/mL) and normal (≥20 ng/mL). Pearson's correlation analysis and covariate-corrected complex logistic regression were performed to evaluate the association between serum 25 (OH) vitamin D level and myopia. Results : Serum 25 (OH) vitamin D level and equivalent spherical refractive power showed a positive correlation (r=0.132, p<0.001). The risk factors for myopia were age, household income, education level, sun exposure, obesity, diabetes, hypertension, cataract, and family history of eye disease. When the serum 25 (OH) vitamin D level was less than 20 ng/mL, the risk of severe myopia increased by 2.55 times (95% confidence interval: 1.27~5.16) even after the risk factors were corrected. Conclusion : High myopia was associated with serum 25 (OH) vitamin D level in Korean.

A comparison between retinoscopy and autorefraction in acceptance of subjective correction in school age children

Discrepancies have been reported between the results of objective refraction obtained with autorefraction (AR), retinoscopy, and the correction which is accepted by patients on subjective refraction. To assess the refractive status of school age children using retinoscopy and autorefraction, and estimate the accuracy of each in acceptance of subjective correction. It was a prospective cohert study. School children of 6-15 years were enrolled for the study, after obtaining informed consent from the parent/guardian and assent from the children. 140 eyes of 70 children were evaluated in this study. Cycloplegia achieved using Cyclopentolate 1% eye drops and was examined by both retinoscopy and autorefraction. Subjective refraction was done and the relative accuracy of both methods with respect to subjective correction was noted. The results were compared and statistical analysis was carried out using Chi-square test with p≤0.05. The spherical power estimated by retinoscopy, was accepted subjectively by 89.3% eyes, while 35% eyes accepted the spherical refractive power estimated by autorefraction. The cylindrical power, estimated by retinoscopy, was accepted by 49.2% eyes, while, 72.8% eyes accepted AR values. Estimation of axis of cylinder on retinoscopy were accepted by 55.7% eyes, while those of autorefraction by 75.7% eyes. The diagnostic accuracy of retinoscopy and autorefraction were comparable, but higher agreement was found with retinoscopy for spherical power component, while autorefraction was slightly better for cylindrical refractive error. Conventional retinoscopy is still the most accurate objective method to estimate the refractive status in children and can be considered a reliable starting point for subjective refraction, however, autorefraction has comparable accuracy and can be a valuable aid to prescribe cylindrical correction.

A retrospective analysis of vision correction and safety in keratoconus patients wearing Toris K soft contact lenses.

The purpose of this study was to investigate the efficacy and safety of the Toris K silicone hydrogel contact lens (SwissLens; Prilly, Switzerland) in keratoconus patients. A database with information on 50 keratoconus patients (64 eyes) fitted with Toris K soft contact lenses over a 2-year period was retrospectively reviewed. Demographic data, prefitting refraction, the reason for choosing the Toris K soft contact lens, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), best-corrected visual acuity with a rigid gas permeable lens (BCVA RGP), best-corrected visual acuity with the Toris K lens (BCVA Toris K), and complications were evaluated. The mean age±standard deviation at the time of fitting was 27.92±9.86years. The mean spherical refractive power was -4.62±6.53 dioptres, and the mean cylinder was -3.78±2.43 dioptres. The most common reason for using Toris K soft contact lenses was an inability to fit the patient with a RGP contact lens. There was a statistically significant difference between UCVA and BCVA Toris K (p=0.0001), as well as between BSCVA and BCVA Toris K (p=0.0001). However, there was no statistically significant difference between BCVA Toris K and BCVA RGP (p=0.20). Superficial punctate keratitis and giant papillary conjunctivitis were the most common complications. The Toris K contact lens is a viable alternative for the optical management of all grades of keratoconus. The Toris K soft contact lens is a promising alternative for the visual rehabilitation of keratoconus patients who cannot tolerate RGP lenses or achieve a good fit.

자동포롭터 내부렌즈의 합성굴절력에 대한 신뢰도 평가

목적: 자동포롭터의 표기 도수와 구면굴절력 및 원주굴절력 실측값을 비교하여 굴절력의 신뢰도를 평가하였다. 방법: 자동포롭터의 마이너스 구면렌즈 및 원주렌즈의 굴절력을 수동렌즈미터로 측정하여 표기도수와의 정확도를 비교하였으며 두 렌즈가 중첩되었을 때의 합성굴절력과 등가구면굴절력을 시험렌즈와 비교 평가하였다. 결과: 포롭터에 내장되어 있는 구면렌즈의 구면굴절력은 70.6%가 표기도수와 0.125 D 이상의 오차가 발생하였으며, 굴절력이 높아질수록 오차값도 증가하였다. 원주렌즈의 단일 원주굴절력은 표기도수와 거의 일치하였다. 포롭터에서 구면렌즈와 원주렌즈가 중첩되었을 때의 합성 구면굴절력은 단일렌즈 구면굴절력과 동일하여 중첩에 의한 구면굴절력의 변화가 없음을 알 수 있었다. 그러나 구면렌즈와 원주렌즈가 중첩되었을 때의 원주굴절력은 표기도수와 큰 차이가 있어 중첩에 의해 영향을 받는다는 것을 알 수 있었다. 포롭터를 이용하여 실측된 등가구면굴절력은 표기도수 및 시험테를 이용한 등가구면굴절력에 비해 낮았으며 고도수일수록 더 낮았다. 결론: 고도의 근시안 또는 근시성 난시 안에서 자동포롭터를 사용하여 시력검사를 하는 경우 표기도수와 차이가 발생하며 과교정이 될 것으로 보여 이에대한 개선이 필요할 것으로 보인다. Purpose: To evaluate the reliability of refractive power by comparing the marked refractive power in an automatic phoropter and actually measured spherical/cylindrical refractive power. Methods: Actual refractive power of minus spherical lens and cylindrical lens in an automatic phoropter was measured by a manual lensmeter and compared with the accuracy of marked refractive power. Furthermore, combined refractive power and spherical equivalent refractive power of two overlapped lenses were compared and evaluated with the refractive power of trial lens. Results: An error of 0.125 D and more against the marked degree was observed in 70.6% of spherical refractive power of spherical lens which is built in phoropter, and the higher error was shown with increasing refractive power. Single cylindrical refractive power of cylindrical lens is almost equivalent to the marked degree. Combined spherical refractive power was equivalent to spherical refractive power of single lens when spherical lens and cylindrical lens were overlapped in a phoropter. Thus, there was no change in spherical refractive power by lens overlapping. However, there was a great difference, which suggest the effect induced by overlapping between cylindrical refractive power and the marked degree when spherical lens and cylindrical lens were overlapped. Spherical equivalent refractive power measured by using a phoropter was lower than that estimated by trial glasses frame and marked degree. The difference was bigger with higher refractive power. Conclusions: When assessment of visual acuity is made by using an automatic phoropter for high myopes or myopic astigmatism, some difference against the marked degree may be produced and they may be overcorrected which suggests that improvement is required.

하워드-돌먼 입체검사를 이용한 20대 성인의 동적 입체시 평가

목적: 본 연구에서는 하워드-돌먼 입체검사(Howard-Dolman test, HDTEST, Bernell, U.S.A)를 이용하여 20대 성인의 동적 입체시를 측정하여 남녀 간의 동적 입체시를 비교하고, 동공 간거리(PD; pupillary distance)와 좌우안의 구면굴절력의 차이로 인한 굴절부등과 동적 입체시의 상관관계를 분석해 보고자 하였다. 방법: 평균연령이 <TEX>$22.68{\pm}0.50$</TEX>(20~29)세인 20대 성인 63명(남자 30명, 여자 33명)을 대상으로 실험을 실시하였다. 굴절이상자는 완전교정을 한 후에 Howard-Dolman test(H-D Test)를 이용하여 2.5 m 검사거리에서 동적 입체시를 각각 5회 측정하였다. 결과: 전체 대상자의 동적 입체시의 평균은 <TEX>$28.44{\pm}25.03$</TEX>초였고, 이들 중 남자는 <TEX>$28.23{\pm}23.34$</TEX>초, 여자는 <TEX>$28.63{\pm}26.83$</TEX>초였다. PD 범위를 기준으로 한 동적 입체시에 있어서 PD가 59.80 mm이하 범위에서는 <TEX>$33.87{\pm}18.53$</TEX>초, 59.81~66.15 mm의 범위에서는 <TEX>$26.24{\pm}25.26$</TEX>초, 66.15 mm를 초과하는 범위에서는 <TEX>$34.60{\pm}25.65$</TEX>초로 나타났고, 유의한 차이는 보이지 않았다(P=0.73, r=0.03). 굴절부등의 차이를 기준으로 할 때 동적 입체시는 굴절부등이 1 D미만인 경우 <TEX>$26.81{\pm}24.86$</TEX>초, 1 D이상인 경우는 <TEX>$1.45{\pm}24.18$</TEX>초였고 유의한 차이는 없었다(P=0.15, r=0.15). 결론: H-D test를 이용해 20대 성인의 동적 입체시를 평가해 보았을 때, 남녀 간에 큰 차이가 없고, PD와 굴절부등은 동적 입체시에 큰 영향을 주지 않는 것으로 나타났다. Purpose: In this study, dynamic stereoacuity of 20s' adults were measured by using the Howard-Dolman test(H-D TEST, Bernell, U.S.A), and compared of male and female. And the correlation between dynamic stereoacuity and PD(pupillary distance), and between dynamic stereoacuity and anisometropia caused by difference in the spherical refractive power of the left and right eyes were analyzed. Methods: The mean age of <TEX>$22.68{\pm}0.50$</TEX>(20~29)years old, 20s' 63 adults (30 male, 33 female) were conducted for this experiments. After the full correction of subject's refractive error, dynamic stereoacuity was measured 5 times for 1 subject at 2.5 m distance using the H-D test. at 2.5 distance. Results: The mean of dynamic stereoacuity was <TEX>$28.44{\pm}25.03$</TEX> sec of arc for total subjects, <TEX>$28.23{\pm}23.34$</TEX> sec of arc for male, and <TEX>$28.63{\pm}26.83$</TEX> sec of arc for female. In the dynamic stereoacuity classified by the range of inter-pupil distance (IPD), the dynamic stereoacuity was <TEX>$33.87{\pm}18.53$</TEX> sec for the IPD being under 59.80 mm, <TEX>$26.24{\pm}25.26$</TEX> sec of arc for 59.81~66.15 mm, <TEX>$34.60{\pm}25.65$</TEX> sec of arc for over 66.15 mm. However, there were no significant differences between 3 groups (P=0.73, r=0.03). In dynamic stereoacuity classified by the refractive error difference between two eyes, dynamic stereoacuity was <TEX>$26.81{\pm}24.86$</TEX> sec of arc for the under 1 D, <TEX>$41.45{\pm}24.18$</TEX> sec of arc for over 1 D, and there was no significant difference between two groups (P=0.15, r=0.15). Conclusions: Dynamic stereacuity by the H-D test in 20s adults showed that there was no significant differences between male and female, and PD and anisometropia did not have a significant impact upon the dynamic stereoacuity.

자동 굴절력계의 굴절력값과 포롭터를 이용한 처방값의 차이에 관한 연구

목적: 자동굴절력계의 굴절력 값과 포롭터를 이용한 안경처방 굴절력 값에서, 굴절값 차이의 대소가 나타나는 조건을 연구하였다. 방법: 자동굴절력계(SR-7000)와 자동포롭터(AV-9000)를 이용하여 안질환이 없고, 굴절 이상으로 근용안경을 착용하는 30명을 대상으로 총 60안을 검사 하였다. 검사자에 기인한 굴절력 처방값의 변화를 방지하기 위하여, 2명의 검사자가 동일한 검사 조건에서 피검사자의 눈을 측정하였다. 결과: 통계적으로 2명의 검사자의 굴절력 처방값은 유의할만한 차이가 없었다. 대부분의 측정값에서 포롭터를 이용한 안경처방 굴절력 값이 자동굴절력계를 통해 측정된 굴절력 값보다 작게 측정되었다. 근시에서 (-)구면 굴절력 값이 클수록 자동굴절력계의 측정값과 자동포롭터 처방값 간의 차이가 증가하는 현상은 찾아 볼 수 있었다. 근시성 난시안에서 난시도수의 구간별로 결과를 분석하였다. 난시도수가 증가할수록 자동굴절력계와 자동포롭터 값 사이의 차이는 적어지는 경향을 확인할 수 있었다. 결론: 2명의 검사자의 처방값 간의 차이는 없었다. 자동굴절력계의 굴절력 값과 포롭터를 이용한 안경처방 굴절력 값 차이는 근시나 근시성 난시의 경우 피검사자의 굴절 이상도에 대략 비례한다. 피검사자의 교정 렌즈의 굴절력이 클수록 굴절력 차이가 증가하므로, 교정 렌즈 처방 시 주의가 요구된다. Purpose: This study is research of the conditions which causes difference between the refractive power of the measurement of autorefractometer and the prescription using phoropter. Methods: Autorefractometer (SR-7000) and phoroptor (AV-9000) were used to measure 60 eyes of 30 participants who had no eye diseases and wore the corrective lens due to Ametropia. To prevent the dependence of the prescription value of the refractive power on the testers, two testers measured the refractive power of the eyes of the participants at the same measuring conditions. Results: Statistically, the prescribed values of the refractive power by two testers were not significantly different. Most of the prescribed values of the refractive power were smaller than the refractive power by autorefractometer In case of myopic eyes, the difference between refractive powers by the measurement of autorefractometer and the prescription using phoropter showed the trend of increase as the spherical refractive power became larger. The result was analyzed by the range of the different cylindrical refractive power for the myopic astigmatic eyes. In this case, the difference between refractive powers showed the trend of decrease as the cylindrical refractive power became larger. Conclusions: No difference between the prescribed value by two testers was observed. In case of myopic or myopic astigmatic eyes, the difference between refractive powers by autorefractometer and the prescription were measured to be approximately proportional to the refractive powers of ametropic eyes. As the this difference become larger for the participant who needs the lens of larger refractive power, additional caution is needed in the prescription of the refractive power of the corrective lens.

시력검사거리에 따른 원거리 시력검사 신뢰성 평가

Purpose: We aimed to evaluate reliability of eye exam for visual acuity as a function of distance. Methods: There were 39 patients (78 eyes) who had visual acuity 1.0 or more at 5 meters. We measured refractive power of patients at each distances, 5 meters, 4 meters and 3 meters. Automatic chart (LCD-700, Hyeseong Optic. Co., Korea) used for visual acuity, skiascope (Beta 200, Heine, Germany) and auto refractometer (RK-5, Canon, Japan) used as for objective refraction. Accommodation was examined by minus lens addition methods, and Accommodative lag was examined by grid chart for reading distance. Results: Being compared to 3 meter test, Amount of corrected spherical refractive power decreased by D, astigmatism decreased by D, and axis of astigmatism rotated toward to temporal by degrees for right eyes, by degrees for left eyes in case of 5 meter test. Changes of corrected refraction and astigmatism were slightly correlated (r=-0.31, r=-0.29). Conclusions: Because corrected refraction power and amount of astigmatism decreased and axis of astigmatism tends to turn the temporal direction according to exam distance, examination distance of visual acuity should improved as to 5 meters.

Reliability and Usefulness of Refractive Measurements by PlusoptiX S09 in Children

Purpose: To compare the refractive measurements obtained using a photorefractor (PlusoptiX S09, PlusoptiX GmbH, Germany) with those obtained using cycloplegic refraction in children. Methods: We assessed the refractive status of 268 eyes in 134 children. The values acquired via photorefraction with a PlusoptiX S09 device were compared with those obtained by cycloplegic retinoscopy. Hyperopia (≥+3.5 D), myopia (≥-3.0 D), with the rule or against the rule astigmatism (≥-1.5 D), and oblique astigmatism (≥-1.0 D) were set as diagnostic criteria for refractive amblyopia risk factors (RARFs). The difference in the detection of RARFs by the two methods was the main outcome measure. Results: The average spherical refractive power was -0.81 ± 1.68 D for PlusoptiX S09 versus -0.26 ± 2.00 D for cycloplegic retinoscopy (average difference -0.54 ± 0.61 D; p < 0.001). The average spherical equivalent was -1.20 ± 1.62 D for PlusoptiX S09 versus -0.64 ± 1.94 D for cycloplegic retinoscopy (average difference -0.56 ± 0.62 D; p < 0.001). The average cylinder power was -0.79 ± 0.93 D for PlusoptiX S09 versus -0.76 ± 0.94 D for cycloplegic retinoscopy (average difference -0.03 ± 0.33 D; p = 0.135). Even though cycloplegic retinoscopy is considered the gold standard, the sensitivity and specificity for detecting RARFs with the PlusoptiX S09 were 88.0% and 96.3%, respectively. Conclusions: PlusoptiX S09 is a relatively useful method for detecting RARFs, but the device tends toward myopic shift compared to cycloplegic refraction, and hyperopia is underestimated. J Korean Ophthalmol Soc 2014;55(7):1071-1076

Rose K Lenses for Keratoconus—An Indian Experience

To describe initial lens selection and our experience of Rose K lens fitting in keratoconus in Indian eyes. Retrospective study of patients who underwent the Rose K contact lens (CL) trial during a 6-month period from July 2007 to December 2007 in a tertiary eye care centre in South India. We obtained data on patient demographics, prefitting refraction and best spectacle-corrected visual acuity, corneal topography data whenever available, number of trials performed, CL parameters, and vision with final CL. The base curve (BC) of the CL and the topographic indices were analyzed to find the correlation. If the coefficient of correlation was significant, the relationship was further examined using multiple regression analysis. A "P" value of <0.05 was considered statistically significant. One hundred twenty-eight eyes of 80 patients who underwent the Rose K trial were included in the study. The group included 50 male patients and the mean age was 21.92 +/- 7.14 years. The mean spherical refractive power was -6.11 +/- 5.76 diopter (range: 0 to -20.00 diopter) and mean cylinder was -4.29 +/- 3.46 diopter (range: 0 to -22). The mean number of CL trial performed was 1.73 +/- 0.9 (range: 1-5). All patients were fitted with the standard Rose K lens with diameter 8.7 mm. The mean BC of the lens was 6.3 +/- 6.02 mm, and the mean power was -11.4 +/- 5.78. The 5-mm average K was the best predictor of the BC of the Rose K lens in all grades of keratoconus. Selecting the BC of the initial trial lens based on the 5-mm average K on the axial map can reduce the complexity and chair time in fitting Rose K lenses in keratoconic eyes.

Ocular Axial Length and Its Associations in an Adult Population of Central Rural India: The Central India Eye and Medical Study

To investigate the normal distribution of axial length of the globe, which is a major measurement of the eye, and its associations with other ocular and systemic parameters. Population-based study. The Central India Eye and Medical Study is a population-based study performed in a rural region of central India. The study comprised 4711 subjects (aged 30+ years) of 5885 eligible individuals (response rate, 80.1%). A detailed ophthalmic and medical examination was performed. The axial length was measured sonographically. Axial length. Axial length measurements were available on 4698 study participants (99.7%). Their mean age was 49.4+/-13.4 years (range, 30-100 years), and the mean refractive error was -0.18+/-1.48 diopters (range, -20.0 to +7.25 diopters). Mean axial length was 22.6+/-0.91 mm (range, 18.22-34.20 mm). In multivariate analysis, axial length was significantly (P<0.001) associated with the systemic parameters of increased age, taller body height, greater body mass index, and higher level of education, and with the ocular parameters of lower best-corrected visual acuity, lower corneal refractive power, deeper anterior chamber, thicker lens, and more myopic spherical power and cylindrical refractive power. Within the highly myopic group, as defined by an axial length that exceeded 26.5 mm, none of these associations (except for the association between axial length and spherical refractive power) were statistically significant (P>0.15) in univariate or multivariate analysis. In a rural population of central India, the mean ocular axial length was 22.6+/-0.91 mm, which was shorter than that of other populations. Axial length was associated with the systemic parameters of increased age, taller body height, greater body mass index, and a higher level of education, and with the ocular parameters of lower best-corrected visual acuity, lower corneal refractive power, deeper anterior chamber, thicker lens, and more myopic spherical and cylindrical refractive power. These associations were valid only for those eyes that were not highly myopic, whereas axial length was associated with refractive error only in highly myopic eyes. Proprietary or commercial disclosure may be found after the references.

Molecular genetics of human myopia: an update.

Myopia, or nearsightedness, is the most common human eye disorder in the world, and is a significant global public health concern. Along with cataract, macular degeneration, infectious disease, and vitamin A deficiency, myopia is one of the most important causes of visual impairment worldwide. Severe or high-grade myopia is a leading cause of blindness because of its associated ocular morbidities of retinal detachment, macular choroidal degeneration, premature cataract, and glaucoma. Ample evidence documents the heritability of the non-syndromic forms of this condition, especially for high-grade myopia, commonly referred to as myopic spherical refractive power of 5 to 6 diopters or higher. Multiple high-grade myopia genetic loci have been identified, and confirmatory studies identifying high-grade and moderate myopia loci have also occurred. In general, myopia susceptibility genes are unknown with few association studies performed, and without confirmation in other research laboratories or testing of separate patient cohorts.