Refractive Status and Biometric Characteristics of Children With Familial Exudative Vitreoretinopathy.

Purpose: To compare biometric characteristics between patients with early-stage familial exudative vitreoretinopathy (FEVR) and healthy controls. Methods: This case-control study included 50 FEVR eyes in stage 1-2 and 50 control eyes matched by age, gender and spherical equivalent (SE). Biometric parameters including axial length (AL), white-to-white diameter (WTW), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), pupil diameter, vitreous chamber depth, anterior and posterior corneal surface curvature radius (ACR and PCR), anterior lens surface curvature radius (ALR) and posterior lens surface curvature radius were measured using IOLMaster 700 and compared between cases and controls using paired t-test. Correlations between SE and biometric measures were assessed using Pearson correlation coefficient (r) in cases and controls. Results: Both FEVR cases and matched controls had a mean age of 7.6 years, 48% female and mean SE of -5.3 D (80% myopia). Compared to controls, FEVR eyes had smaller AL (P = 0.009), WTW (P = 0.001), ACD (P < 0.001), and ALR (P = 0.03), but larger CCT (P = 0.02) and LT (P = 0.01). In FEVR eyes, SE was negatively correlated with AL (r = -0.79, P < 0.001), positively correlated with ACR (r = 0.29, P = 0.04) and PCR (r = 0.33, P = 0.02), whereas in controls, SE was negatively correlated with AL (r = -0.82, P < 0.001) and LT (r = -0.34, P = 0.02), positively correlated with ALR (r = 0.29, P = 0.04). Conclusions: Patients at early stage of FEVR exhibited a unique eye morphology resembling ocular development arrest, which may help to develop screening and early detection tools for FEVR. In FEVR patients, myopia is very prevalent and significantly associated with corneal curvature increase.

Investigation of contrast visual acuity with rigid gas permeable contact lenses after penetrating Keratoplasty.

BACKGROUND: To investigate the effects of rigid gas permeable contact lens (RGP-CL) wear on contrast visual acuity in patients after penetrating keratoplasty. METHODS: Nineteen patients (19 eyes), aged 30.45 ± 5.83 years, who had received penetrating keratoplasty and were successfully fitted with RGP-CLs at our hospital from July 2017 to June 2018 were included. Contrast visual acuities at 100%, 25%, and 10% with spectacles and RGP-CLs were analyzed using the Chi-square test. The wavefront aberrations at the anterior surface of the cornea before and 1 month after RGP-CL wear were compared using the matched sample t-test. RESULTS: The mean best spectacle-corrected visual acuities were 0.390 ± 0.135 logMAR, 0.706 ± 0.182 logMAR, and 0.952 ± 0.223 logMAR at the 100%, 25%, and 10% contrast levels, respectively, which were significantly lower than the RGP-CL-corrected visions at the three levels (0.255 ± 0.133 logMAR, 0.488 ± 0.168 logMAR, and 0.737 ± 0.159 logMAR; all P < 0.001). The vision losses with RGP-CLs were 0.231 ± 0.099 logMAR and 0.466 ± 0.094 logMAR at the 25% and 10% contrast levels, respectively. The Zernike spherical aberration Z04 was reduced from 3.734 ± 1.061 µm to 2.622 ± 0.725 µm after wearing the RGP-CLs (P ≤ 0.001). The astigmatism parameters of Z- 22 and Z22 were also reduced from 3.761 ± 2.309 µm and 3.316 ± 2.147 µm to 2.637 ± 1.722 µm and 2.016 ± 1.184 µm, respectively (P < 0.05). CONCLUSION: For post-keratoplasty patients, RGP-CLs can help to improve visual performance, especially low contrast visual acuity. The improvement may be related to the reduction of corneal aberrations, mainly the spherical and astigmatism aberrations.

Study of the Biological Developmental Characteristics of the Eye in Children After Laser Surgery for the Treatment of Retinopathy of Prematurity.

OBJECTIVE: To observe the differences in ocular biology between premature infants who had undergone retinal laser photocoagulation (LP) for retinopathy of prematurity (ROP) and full-term infants and to investigate the relationships between these differences and the development of the refractive state. METHODS: This retrospective, cross-sectional study included 25 children (50 eyes) who had undergone laser treatment for aggressive posterior retinopathy of prematurity (AP-ROP), ROP in zone I requiring treatment, or ROP in zone II requiring treatment in the posterior pole (laser group) and 29 full-term infants (58 eyes) who had not (control group). Basic information, spherical equivalent (SE), and best corrected visual acuity (BCVA) were collected from the two groups. Their mean ages were 7.32 ± 2.85 and 7.34 ± 2.57 years, respectively (t = -0.047, P = 0.96). Ocular biology data were measured using an IOL Master 700 instrument (Carl Zeiss Meditec AG) and the data were processed using MATLAB (R2016a, Mathworks Inc.). The data markers included central corneal thickness (CCT), anterior and posterior surface corneal curvature radius (CCR), anterior chamber depth (ACD), lens thickness (LT), lens anterior surface curvature radius, lens posterior surface curvature radius, and eye axis length (AL). Optometric data were collected simultaneously and all BCVA values were converted to the logarithm of the minimum angle of resolution (LogMAR) for analysis. The data were statistically analyzed using SPSS software (V.23.0). Independent sample t-tests were used for the assessment of ocular biology and refractive indices in both groups of children and Pearson correlation coefficients were used to evaluate the correlations between age, gestational age at birth and ocular biology structural parameters. P < 0.05 was considered statistically significant. RESULTS: Comparisons of ocular biomarkers, refractive status, and BCVA between children in the laser and control groups showed relationships among ocular biomarkers, including the corneal-related parameters of CCT (0.54 ± 0.04 mm and 0.56 ± 0.03 mm, t = -2.116, P < 0.05), anterior surface CCR (7.53 ± 0.33 mm and 7.84 ± 0.30 mm, t = -5.063, P < 0.05), posterior surface CCR (6.75 ± 0.34 mm and 7.03 ± 0.24 mm, t = -4.864, P < 0.05); as well as those related to anterior chamber depth (ACD) were 3.24 ± 0.26 mm and 3.64 ± 0.26 mm, respectively (t = -8.065, P < 0.05), lens-related parameters (LT) were 3.80 ± 0.19 mm and 3.45 ± 0.16 mm, respectively (t = 10.514, P < 0.05); anterior lens surface curvature radius were 10.02 ± 0.93 mm and 10.52 ± 0.85 mm, respectively (t = -2.962, P < 0.05); posterior lens surface curvature radius were 5.55 ± 0.51 mm and 5.80 ± 0.36 mm, respectively (t = -2.917, P < 0.05), and ocular axis (AL) were 22.60 ± 1.42 mm and 23.45 ± 1.23 mm, respectively (t = -3.332, P < 0.05). Moreover, comparison of refractive status and BCVA between two groups of children showed an SE of -1.23 ± 3.38 D and -0.07 ± 2.00 D (t = -2.206, P < 0.05) and LogMAR (BCVA) of 0.12 ± 0.13 and 0.05 ± 0.11 (t = 3.070, P < 0.05). Analysis of the correlations between age and ocular biomarkers and refractive status of children in the laser and control groups showed correlations between age and ocular biomarkers in the two groups, in which age in the laser group was positively correlated with AL (r = 0.625, P < 0.05) but not with other biomarkers (P > 0.05). Age in the control group was negatively correlated with CCT, ACD, and AL (r = 0.303, 0.468, 0.703, P < 0.05), as well as with LT (r = -0.555, P < 0.05), with no correlation with other biomarkers (P > 0.05). Analysis of the correlation between age and refractive status of children in both groups showed that the age of children in both laser and control groups was negatively correlated with SE (r = -0.528, -0.655, P < 0.05) and LogMAR (BCVA) (r = -0.538, -0.542, P < 0.05). Analysis of the correlations between refractive status and ocular biomarkers in children in the laser and control groups showed that the refractive status in children in the laser group was negatively correlated with AL (r = -0.773, P < 0.05) but not with other biomarkers in this group (P > 0.05). The refractive status of children in the control group was negatively correlated with ACD and AL (r = -0.469, -0.734, P < 0.05), positively correlated with LT (r = 0.364, P < 0.05), and was not correlated with other biomarkers in this group (P > 0.05). Analysis of the correlations of gestational age at birth with ocular biomarkers and refractive status in children in the laser group showed a positive correlation between gestational age at birth and AL (r = 0.435, P < 0.05) but no other correlations with the other biomarkers (P > 0.05). Moreover, gestational age at birth was negatively correlated with SE (r = -0.334, P < 0.05) and LogMAR (BCVA) (r = -0.307, P < 0.05) in children in the laser group. CONCLUSIONS: Compared to full-term infants, the development of CCT, ACD, LT, and AL was relatively delayed after ROP laser surgery, resulting in thin central corneal thickness, steep corneas, shallow anterior chambers, thicker lenses, "rounder" lens morphology, increased refractive power, and short eye axes, leading to the development of myopia. The changes in refractive status were mainly influenced by increased lens thickness. The results of this study showed that the lower the gestational age at birth, the greater the effects on emmetropization in children after ROP, and the more likely the development of myopia.

[The key parameters of design research and analysis of the Chinese reading visual acuity chart].

OBJECTIVE: Reading is a visual function human being used to understand environmental events based on writing materials. This study investigated the feasibility of reading visual acuity chart in assessment of reading ability by analysis of the key factors involved in the design of the visual acuity chart. METHODS: The reading level was determined as grade 3 primary school with Song as the font and 30 characters included in the sentences. Each of the sentences consisted of 27 commonly-used Chinese characters (9 characters between any two punctuations) and 3 punctuations. There were no contextual clues between the 80 sentences selected. The characters had 13 different sizes with an increment of 0.1 log unit (e.g.1.2589) and 2.5 pt was determined as the critical threshold. Readable test for visual target was followed as (1) 29 candidates with a raw or corrected visual acuity (VA)of at least 1.0 were selected to read 80 selected sentences with the size of characters of 2.5 pt at a distance of 40 cm, (2) the time used for reading with the number of characters wrongly read was recorded, (3) 39 sentences were selected as visual targets based on reading speed, effective reading position and total number of character strokes, (4) The 39 selected sentences were then randomly divided into 3 groups with no significant difference among the groups in the 3 factors listed at (3) with paired t-test. RESULTS: This reading visual chart was at level of Grade 3 primary school with a total stroke number of 165-210(Mean 185 ± 10), 13 font sizes a 0.1 log unit increment, a song pattern and 2.5 pt as the critical threshold. All candidates achieved 100% correct in reading test under 2.5 pt with an effective reading speed as 120.65-162 wpm (Mean 142.93 ± 11.80) and effective reading position as 36.03-61.48(Mean 48.85 ± 6.81). The reading test for the 3 groups of sentences showed effective reading speed as (142.49 ± 12.14) wpm,(142.86 ± 12.55) wpm and (143.44 ± 11.63) wpm respectively(t1-2 = -0.899, t2-3 = -1.295, t1-3 = -1.435). The reading position was 48.55 ± 6.69, 48.99 ± 7.49 and 49.00 ± 6.76, respectively(t1-2 = -1.019, t2-3 = -0.019, t1-3 = -0.816). The total number of character strokes was 185.54 ± 7.55, 187.69 ± 13.76 and 182.62 ± 8.17, respectively(t1-2 = 0.191, t2-3 = 1.385, t1-3 = 1.686). CONCLUSIONS: A practical design of the Chinese reading visual chart should consider size, increment, legibility in selection of reading sentences. Reading visual acuity, critical threshold and effective reading speed could be used to express the reading visual function.

Higher order aberrations and low contrast vision function in myopic eyes (-3.00 to -6.00 d) under mesopic conditions.

PURPOSE: To investigate the relationship between higher order aberrations and low contrast visual acuity in myopic eyes under mesopic conditions. METHODS: This prospective, observational case series included 52 patients (29 women, 23 men) aged 18 to 35 years. Ocular higher order aberration was measured under mesopic conditions using the Hartmann-Shack wavefront analyzer, and high (100%) and low contrast (5%, 10%, and 25%) visual acuity was measured using a multi-function visual acuity tester under the same conditions. RESULTS: Multiple linear regression analysis revealed that spherical aberrations were significantly associated with low contrast visual acuity at a low contrast level. The correlation coefficients of spherical-like aberration (S(4)) were 0.393, 0.315, and 0.419 at 5%, 10%, and 25%, respectively (P=.004, .023, and .002, respectively). The correlation coefficient of spherical aberration ( C40) was 0.373 at the 5% contrast visual acuity level (P=.006). However, coma and other higher order aberrations did not correlate statistically (P>.05). CONCLUSIONS: Relationships exist between S(4) and C40 and low contrast visual acuity. Effects on low contrast visual acuity increase with the value of spherical aberration. This suggests that less spherical aberration may provide optimal visual function under night conditions.

[Research on measurement of rigid contact lens eccentricity based on reflection].

Rigid contact lenses with eccentricity through manufacture can more or less influence visual correction or induce the corneal warpage. Therefore the fine detection of rigid contact lens eccentricity is needed and important. This study was aimed to design a system for lens eccentricity measurement by the principle of optical reflection. By using a standard concave mirror in the center of lens jig, the geometrical center of a lens could be detected accurately. It has solved the problem of lens distortion and breakableness attributed to the conventional method based on rotating reflection. The system is proved to be of practical method with good repeatability.

[Selection of Chinese visual targets by fourier frequency spectrum analysis].

OBJECTIVE: To select Chinese characters for Chinese visual acuity chart by using the method of Fourier frequency spectrum analysis. METHODS: BMP images were made for 1062 Chinese characters with small or medium number of strokes. The images were processed to derive frequency spectrum at the frequency domain by using a MatLab program. Euclidean distance from Cluster analysis was then used to classify and select the Chinese characters for optotypes of the visual acuity chart, based on their mean frequency spectrum from all the characters analyzed. RESULTS: Fifty and forty Chinese characters were selected from the groups of the small and the middle number of strokes respectively. CONCLUSIONS: It is important and interesting to select Chinese characters by using Fourier analysis method for designing Chinese visual acuity chart that is consisting with the property of the visual system of the eye.

[The relationship between corneal astigmatism with a vector-based method and whole eye second order wavefront aberrations].

OBJECTIVE: To investigate the relationship between corneal astigmatism and second order wavefront aberration in myopic eyes. METHODS: The corneal astigmatism and the whole eye wavefront aberrations of both eyes of 246 subjects were measured using the Humphrey corneal topography and the WASCA wavefront analyzer. According to axial of the corneal astigmatism, the subjects were divided into five groups (WR(0), WR(180), AR, OA(45) and OA(135)). The corneal astigmatism was decomposed into J(45) and J(0) with a Vector-based method, and correlated with the 2nd order Zernike aberrations (C(3) and C(5)). RESULTS: The mean corneal astigmatisms for the five groups were -1.34 D x 6.87 degrees, -1.03 D x 23.15 degrees, -0.48 D x 89.55 degrees, -0.91 D x 156.87 degrees and -1.02 D x 176.74 degrees respectively. Most of the corneal J(45) and J(0) components were correlated significantly with the C(3) and the C(5) aberrations in the whole eye. While the correlation coefficients (R(2)) between the J(45) and the C(3) were 0.138, 0.119, 0.090, 0.526 and 0.501, the R(2) between the J(0) and the C(5) were 0.711, 0.736, 0.864, 0.866 and 0.785 for the five groups respectively. CONCLUSIONS: The corneal astigmatism plays an important role in determining the 2nd order wavefront aberration in the whole eye, and the combination processes between the corneal and internal astigmatism (compensation and/or addition) change with the axial of the corneal astigmatism.