Original Article

Changes in crystalline lens parameters during accommodation evaluated using swept source anterior segment optical coherence tomography

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Backgrounds: To assess changes in anterior segment biometry during accommodation using a swept source anterior segment optical coherence tomography (SS-OCT).

Methods: One hundred-forty participants were consecutively recruited in the current study. Each participant underwent SS-OCT scanning at 0 and ?3 diopter (D) accommodative stress after refractive compensation, and ocular parameters including anterior chamber depth (ACD), anterior and posterior lens curvature, lens thickness (LT) and lens diameter were recorded. Anterior segment length (ASL) was defined as ACD plus LT. Lens central point (LCP) was defined as ACD plus half of the LT. The accommodative response was calculated as changes in total optical power during accommodation.

Results: Compared to non-accommodative status, ACD (2.952±0.402 vs. 2.904±0.382 mm, P<0.001), anterior (10.771±1.801 vs. 10.086±1.571 mm, P<0.001) and posterior lens curvature (5.894±0.435 vs. 5.767±0.420 mm, P<0.001), lens diameter (9.829±0.338 vs. 9.695±0.358 mm, P<0.001) and LCP (4.925±0.274 vs. 4.900±0.259 mm, P=0.010) tended to decreased and LT thickened (9.829±0.338 vs. 9.695±0.358 mm, P<0.001), while ASL (6.903±0.279 vs. 6.898±0.268 mm, P=0.568) did not change significantly during accommodation. Younger age (β=0.029, 95% CI: 0.020 to 0.038, P<0.001) and larger anterior lens curvature (β=?0.071, 95% CI: ?0.138 to ?0.003, P=0.040) were associated with accommodation induced greater steeping amplitude of anterior lens curvature. The optical eye power at 0 and ?3 D accommodative stress was 62.486±2.284 and 63.274±2.290 D, respectively (P<0.001). Age was an independent factor of accommodative response (β=?0.027, 95% CI: ?0.038 to ?0.016, P<0.001).

Conclusions: During ?3 D accommodative stress, the anterior and posterior lens curvature steepened, followed by thickened LT, fronted LCP and shallowed ACD. The accommodative response of ?3 D stimulus is age-dependent.

Original Article

Subjective refractions determined by Dyop? and LogMAR chart as fixation targets

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Background: Dyop® is a dynamic optotype with a rotating and segmented visual stimulus. It can be used for visual acuity and refractive error measurement. The objective of the study was to compare refractive error measurement using the Dyop® acuity and LogMAR E charts.

Methods: Fifty subjects aged 18 or above with aided visual acuity better than 6/12 were recruited. Refractive error was measured by subjective refraction methods using the Dyop® acuity chart and LogMAR E charts and the duration of measurement compared. Thibo’s notation was used to represent the refractive error obtained for analysis.

Results: There was no significant difference in terms of spherical equivalent (M) (P=0.96) or J0 (P=0.78) and J45 (P=0.51) components measured using the Dyop® acuity and LogMAR E charts. However, subjective refraction measurement was significantly faster using the Dyop® acuity chart (t=4.46, P<0.05), with an average measurement time of 419.90±91.17 versus 452.04±74.71 seconds using the LogMAR E chart.

Conclusions: Accuracy of refractive error measurement using a Dyop® chart was comparable with use of a LogMAR E chart. The dynamic optotype Dyop® could be considered as an alternative fixation target to be used in subjective refraction.

Review Article

Psychophysics in the ophthalmological practice—I. visual acuity

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Perception is the ability to see, hear, or become aware of external stimuli through the senses. Visual stimuli are electromagnetic waves that interact with the eye and elicit a sensation. Sensations, indeed, imply the detection, resolution, and recognition of objects and images, and their accuracy depends on the integrity of the visual system. In clinical practice, evaluating the integrity of the visual system relies greatly on the assessment of visual acuity, that is to say on the capacity to identify a signal. Visual acuity, indeed, is of utmost importance for diagnosing and monitoring ophthalmological diseases. Visual acuity is a function that detects the presence of a stimulation (a signal) and resolves its detail(s). This is the case of a symbol like “E”: the stimulus is detected, then it is resolved as three horizontal bars and a vertical bar. In fact, within the clinical setting visual acuity is usually measured with alphanumeric symbols and is a three-step process that involves not only detection and resolution, but, due to the semantic content of letters and numbers, their recognition. Along with subjective (psychophysical) procedures, objective methods that do not require the active participation of the observer have been proposed to estimate visual acuity in non-collaborating subjects, malingerers, or toddlers. This paper aims to explain the psychophysical rationale underlying the measurement of visual acuity and revise the most common procedures used for its assessment.
Editorial
Original Article

Supracapsular implantation with optic capture of posterior chamber intraocular lens in Chinese children with aphakic after traumatic cataract

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Background: To assess the safety and efficacy of supracapsular implantation with optic capture of the posterior chamber intraocular lens in Chinese children with aphakic after traumatic cataract.

Methods: It was a retrospective case series study. Fifteen cases (15 eyes) Chinese children received supracapsular implantation with optic capture of the posterior chamber intraocular lens. Pre- and post-operative visual acuities were recorded. Intra- and post-operative complications were observed. The follow-up period ranged from 7 to 43 (28.7±7.2) months.

Results: Implantation of optic capture of the posterior chamber intraocular lens was successfully performed in 15 eyes. The best corrected visual acuity (BCVA) ranged from 0.3 to 1.0 (0.61±0.19). No optic axis opaque was found in 15 eyes with optic capture. The major complications of optic capture were iris posterior synechia and intraocular lens (IOL) precipitates. Intraocular dislocation was found in one case three weeks after the operation.

Conclusions: Supracapsular implantation with optic capture of the posterior chamber intraocular lens is safe and effective for the treatment of traumatic cataract in Chinese children.

Review Article
Original Article
Original Article

Simplified pupilloplasty technique through a corneal paracentesis to manage small iris coloboma or traumatic iris defect

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Background: To report a new simplified surgical technique to manage small iris coloboma or traumatic iris defect.

Methods: A new surgical technique in which simplified pupilloplasty technique through only a clear corneal paracentesis to manage the iris coloboma or traumatic iris defect within the 120° range was designed. A retrospective revision of the medical records of patients treated with this technique between the years 2013 and 2016 was made. Six eyes of six patients with iris coloboma or traumatic iris defect treated with this new technique were included.

Results: All the operated eyes quickly recovered with central round pupil, negligible complications, inessential symptoms of photophobia and glare, and mild inflammation after a median follow-up time of 22 months (range: 6–34 months).

Conclusions: The simplified pupilloplasty technique presented here could be a good alternative for the management of small iris coloboma or traumatic iris defect.

Original Article

Combined pars plana vitrectomy and suture less scleral fixation of foldable intraocular lens: single surgery visual rehabilitation of dislocated lens/intraocular lens

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Background: To evaluate efficacy and safety of combined pars plana vitrectomy (PPV) and scleral fixated intraocular lens (SFIOL) surgery as a single procedure.

Methods: Retrospective interventional case series done at a tertiary eye care center in Northern India. Eleven patients who underwent combined PPV and SFIOL surgery were included and analyzed retrospectively.

Results: Mean age of the patients was 43.36±15.12 years (range, 22–64 years). Eight were male. Mean baseline best corrected visual acuity (BCVA) was 0.78±0.63 logMAR units while the mean post-operative BCVA at 6 months follow-up was 0.37±0.29 logMAR units, the visual gain being statistically significant (P=0.021). None of the patients had a drop in BCVA with nine patients having final BCVA better than 0.48 logMAR units. Choroidal detachment (CD) was the only notable complication, seen in three patients. Other complications included two cases of intraoperative retinal breaks, a case each of reversible corneal edema, ocular hypertension and cystoid macular edema.

Conclusions: Combined PPV and SFIOL is an efficacious procedure for managing IOL/lens dislocation and aphakia in a single surgery. There may be short-term reversible complications with no impact on final visual gain.

Review Article

RAF near point rule for near point of convergence—a short review

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Abstract: RAF near point rule (RNPR) is a routinely used instrument in ophthalmology and optometry practice as well as for research purposes to measure the near point of convergence (NPC). The measurement of NPC is an important criterion for diagnosis and management of convergence insufficiency. The RNPR forms an important tool for ophthalmic clinicians however, only a very little is understood about it. This article tries to describe and review the designs, measurement techniques, merits and demerits of the RNPR and establish the need for its modification. It recommends that clinicians and researchers consider these findings while measuring NPC with the RNPR.

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  • 眼科学报

    主管:中华人民共和国教育部
    主办:中山大学
    承办:中山大学中山眼科中心
    主编:林浩添
    主管:中华人民共和国教育部
    主办:中山大学
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  • Eye Science

    主管:中华人民共和国教育部
    主办:中山大学
    承办:中山大学中山眼科中心
    主编:林浩添
    主管:中华人民共和国教育部
    主办:中山大学
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