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  5. FP150 : RANGE OF NEAR VISUAL ACUITY IN CHILDREN WITH PSEUDOPHAKIA

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Dr. Deepa John, J11405, Dr. Thomas kuriakose

INTRODUCTION

Accommodation is ability to see over a range of distance by changing the power of the natural lens. With cataract surgery this ability is partially or completely abolished.Apparent accommodation or pseudo-accommodation is the potential of pseudophakic eyes to sustain a good amount of near vision.

AIM

Aim of our study was to measure the range of near vision in children with pseudophakia.Our objective was tomeasure the range of near visual acuity and the minimum amount of near add required by the child to achieve 1M(0.4 decimal) with distance vision correction alone in place.

MATERIALS AND METHODS

 A cross sectionalstudy was conducted after obtaining approval by the institutional review board. Children between the ages of 5 – 15 years with unilateral/ bilateral pseudophakia were included. Children who were mentally challenged were excluded.In children with bilateral pseudophakia, both eyes were assessed and right eye parameters were taken for the analysis. A subjective and objective refraction was done by a pediatric optometrist.  Distance vision assessment was done using Lea symbol log MAR (minimum angle of resolution) visual acuity chart at 3 meters and near vision was assessed using Lea symbol log MAR chart at 30 and 40 cm. Near vision assessment was done unaided and with distant vision spectacle correction alone in place. Minimum spherical power needed to read 1M (0.4 decimal) and the spherical power needed to read child’s class text book (English/Tamil/both) were done with distant vision in place.

RESULTS

A total of 64children were included in the study.Twenty children were between 5-10 years and 44 children were between > 10 -15 years.19 (29.7%) among them were female and 45 (70%)were male.Thirty five (54.7%) children presented with unilateral pseudophakia and 29 (45.3%) with bilateral pseudophakia. Out of 35 children 18 (28%) had right eye pseudophakia and 17(26.6%) had left eye pseudophakia. For all with bilateral pseudophakia, right eye parameters were taken for analysisThe near vision range that children with pseudophakia could read unaided at 30 cm. in which 16 (25%) children could read 1M, 15 (23.4%) children were able to read 1.25M and 10 (15.6%) were able to read 1.6M. More than 50 % could read < 2M unaided at 30 cm. 25 (39.1%) children were able to read 1M with their present glasses. At 30 cm, nine (14.1%) children were able to read 1 M without any additional near vision correction with their distant vision correction in situ, while another 13 (20.3 %) could read 1M with +1diopter alone.

DISCUSSION

Our study included 64 children. Distance and near visual acuity was assessed using log MAR chart. Near vision was assessed using near lea symbol log MAR chartat 30 cm and 40 cm. We also assessed their functional vision using their class text book. Near vision assessment without any spectacle correction showed that > 50% could read < 2M at 30 cm.There was also an increase in the percentage (39 % to 56%) of children who could read IM using their spectacle as compared to new refraction, suggesting requirement of frequent refraction in these children.

Our study showed that with distant vision correction alone in place, 14 % could read 1M at 30 cm stating their ability to accommodate about 3diopter. 61 % required only ≤ 2diopter to read 1 M at 30 cm suggesting a minimum of 1diopter retained accommodation. The ability to read unaided and aided at 30 cm was compared with that at 40 cm.where 4% children could read  1Mat 40 cm stating their ability to accommodate about 3 diopter.57% required only ≤2diopter to read 1M at 40 cm suggesting a minimum of 1diopter retained accommodation.  This showed that smaller fonts were read better at a closer distance (30cm) suggesting that linear magnification might be the reason for this. There was no difference in those who could read English as compared to Tamil, suggesting that the type of letter do not have a role in the ability to readirrespective of the refractive error of the child. Also 1/3 rd of children could read their class text books without any spectacles. 61% required only 2diopter to read 1 M, suggesting a minimum of 1diopter of retained accommodation and they required only a minimum near vision add.

CONCLUSIONS

More than 50% of children with pseudophakia were able to read normal print size (1.25M) without any spectacles, suggesting they could be spectacle free for near work.Only 1/3 rd of children with pseudophakia required spectacles for their near work.

14 % could read 1M at 30 cm with only distant vision correction in place suggesting their ability to accommodate. These children can be without bifocal spectacles. 64 % required only ≤ 2diopter to read 1 M, suggesting a minimum of 1diopter of retained accommodation and they required only a minimum near vision add. The ability to read (unaided and aided) at 30 cm was better for smaller fonts than at 40 cm suggesting a role of linear magnification.  There was no difference in those who could read English as compared to Tamil, suggesting that the type of letter do not have a role in the ability to read irrespective of the refractive error of the child.  1/3 rd of children could read their class text books without any spectacles, suggesting a good functional vision and that they can be spectacle independent during class work .

Reference

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