|Year : 2015 | Volume
| Issue : 2 | Page : 77-79
Is post mydriatic test necessary in children having compound myopic astigmatism?
Mihir Kothari1, Ali Hussain2
1 Department of Pediatric Ophthalmology of Aditya Jyot Eye Hospital Private Limited, Wadala; Bombay City Eye Institute and Research Centre, Mumbai; Jyotirmay Eye Clinic, Thane, Maharashtra, India
2 Department of Pediatric Ophthalmology of Aditya Jyot Eye Hospital Private Limited, Wadala, Mumbai, India
|Date of Submission||02-Jan-2014|
|Date of Acceptance||06-Dec-2014|
|Date of Web Publication||7-May-2015|
Director, Jyotirmay Eye Clinic and Pediatric Low Vision Center, 205 Ganatra Estate, Next to Punjani Indu. Estate, Pokhran Road No 1, Thane West - 400 601, Maharashtra
Source of Support: None, Conflict of Interest: None
Purpose: To study the need of post mydriatic test (PMT) in children with mild to moderate compound myopic astigmatism. Materials and Methods: The children having mild to moderate compound myopic astigmatism presenting to the pediatric ophthalmology department underwent subjective refraction before, immediately after cycloplegia and 3 days after cycloplegia. The refractive error was analyzed using two-tailed paired t test by dividing the refractive-errors into sphere, cylinder and axis. Spherical equivalent was analyzed separately. Result: Eighty four eyes of 42 children aged 3 to16 years (Mean 9.6, SD 3.2) were included. Mean sphere was -0.9 diopter sphere (DS) (± 1.9) without cycloplegia and -0.4 DS (± 2.0) with cycloplegia compared to -0.9 DS (± 1.8) in the PMT. Mean cylinder was -1.3 diopter cylinder (DC) (± 1.2) without cycloplegia and -1.0 DC (± 1.5) with cycloplegia compared to -1.14 DC (± 1.3) in PMT. Mean spherical equivalent was -1.5 DS (± 1.6) without cycloplegia and -0.9 DS (± 1.8) with cycloplegia compared to -1.5 DS (± 1.6) in PMT. For spherical equivalent, the correlation coefficient (r) between non-cycloplegic refraction and cycloplegic refraction; non-cycloplegic refraction and PMT; cycloplegic refraction and PMT was 0.9. However, in comparison to cycloplegic refraction, PMT was closer to non-cycloplegic refraction and differed by only 0.01 DS (± 0.9) in sphere and 0.2 D (± 0.7) in cylinder. Conclusion: PMT is not warranted in children with compound myopic astigmatism.
Keywords: Autorefraction, cycloplegic refraction, post mydriatic test, refraction in children, subjective refraction
|How to cite this article:|
Kothari M, Hussain A. Is post mydriatic test necessary in children having compound myopic astigmatism?. J Clin Ophthalmol Res 2015;3:77-9
|How to cite this URL:|
Kothari M, Hussain A. Is post mydriatic test necessary in children having compound myopic astigmatism?. J Clin Ophthalmol Res [serial online] 2015 [cited 2023 Mar 24];3:77-9. Available from: https://www.jcor.in/text.asp?2015/3/2/77/156587
Cycloplegia helps to uncover the latent component in hypermetropes and relaxes accommodative spasm in myopes thereby reducing undercorrections in hyperopes and overcorrections in myopes. ,, Most investigators recommend cycloplegic refraction to correct ametropia in children. 
Adequate cycloplegia in pigmented races often require multiple topical application of cyclopentolate, homatropine or atropine eye drops.  Although it is agreed that cycloplegia is necessary for refraction in children, despite the attendant side effects (such as prolonged difficulty in near work, photophobia and other systemic adverse effects)  and increase in the patient waiting time, same is not true for post mydriatic test (PMT). For PMT, a patient is recalled for subjective refraction, usually three or four days later, when the effect of cycloplegia and mydriasis has completely disappeared. Despite a lack of evidence that PMT adds any value to the spectacle prescription of the myopic children, it is performed as a routine (read as tradition) in older children in many eye hospitals and eye clinics in India.
PMT increases the cost of eye care and the inconvenience to the patient because of the extra visit needed. In this study, we have compared the refraction of myopic children before and after cycloplegia with PMT and conclude that the traditional practice of doing routine PMT for every patient is not warranted.
| Materials and Methods|| |
This prospective, observational cohort study was done in the Department of Pediatric-Ophthalmology, at a tertiary teaching eye care center in western India. Children cooperative for subjective and objective refraction aged between 4-16 years with myopia between -0.25 DS and -6 DS, astigmatism ≥0.50 D and spherical equivalent ≥ −1.50 D were included in the study. Children aged 3 years or less and those with the best corrected visual acuity less than 20/20, media opacity, nystagmus, squint or any other ocular comorbidity were excluded. Patients were examined on Topcon Autorefractometer RM-6000B (Topcon Corporation, Japan). The patient was seated on an ophthalmic chair (Plantech PO-EU, Gujarat, India). Care was taken to stabilize the head on the chin rest while the forehead touched the forehead band and eyes leveled to the eye level marker. Children were allowed to keep both their eyes open while the optometrist took 3 readings manually according to the standard operating protocol mentioned in the user's manual. An average of three readings was used for refraction. Readings with standard deviation of more than 0.12 were excluded and a repeat of three readings was taken. The subjective refraction was started with the autorefractor readings.
Cycloplegia was attained with three instillation of cyclopentolate eye drops (Cyclopent 1%, Sun Pharmaceutical Ltd, India), in the inferior cul de sac every 15 minutes. Cycloplegic autorefraction was done after 45 minutes again repeating the subjective refraction starting from the autorefractor readings. The final spectacle prescription was given after performing the subjective refraction (PMT) performed at least 3 days later starting with the prior autorefractor reading obtained under cycloplegia. The final prescription was balanced with the duochrome test to refine the spherical monocular end point. 
The non-cycloplegic refraction was defined as the subjectively refined spectacle prescription from the values obtained from the autorefraction under non-cycloplegic condition. The cycloplegic refraction was defined as the subjectively refined spectacle prescription obtained under cycloplegic condition from the values obtained from the autorefraction under cycloplegic condition. PMT was defined as the subjectively refined spectacle prescription obtained under non-cycloplegic condition from the values obtained from the cycloplegic autorefraction. It was performed at least 3 days after the cycloplegic autorefraction was performed. The data was entered in MS Excel, version Windows 2000 (Microsoft Corporation (I) Pvt. Ltd., Gurgaon, India). The refractive error was analyzed by dividing it into three components (sphere, cylinder, and axis). The spherical equivalent was analyzed separately. The p value for the difference of mean was calculated using two-tailed paired t test. The Pearson correlation coefficient (r) was calculated for the set of data obtained from cycloplegic verses non-cycloplegic refraction and the final spectacle prescription after PMT. Sample size calculation  was done for continuous paired variable using the Formula: Z1-α/2 - Z [1-β] 2 Sc 2 /d 2 with 5% significance level i.e., Z1-α/2 = 1.96, standard normal variate as 80% (Z 1-β = -0.84), the standard deviation of the controlled group (Sc) was 1.63, and the effect size (d) was 50. By this calculation, we were required to recruit 83.32 eyes for this study.
| Results|| |
Eighty-four eyes of 42 children aged between 3 and 16 years (Mean 9.60, SD 3.18) of which 20 were males were included in the study. The spherical equivalent and the sphere were significantly reduced after cycloplegia [Table 1] and [Table 2]. The correlation coefficient between the non-cycloplegic refraction, cycloplegic refraction and PMT for the spherical equivalent and sphere was 0.9. There was no significant difference between non-cycloplegic refraction and PMT.
|Table 1: Mean refractive error-sphere, cylinder and axis; without cycloplegia (non-cycloplegic refraction), with cycloplegia and with post mydriatic test (PMT) |
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|Table 2: Difference in the mean refractive errors (sphere, cylinder, axis and spherical equivalent) under non-cycloplegic condition and cycloplegic conditions with post mydriatic test (PMT) |
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| Discussion|| |
The refractive surgeons have questioned the routine use of strong cycloplegics in young adult ametropes undergoing refractive surgery for the correction of ametropia.  The refraction obtained in the myopic children with tropicamide 1% was similar to 1% topical cyclopentolate.  There is an increasing trend toward using faster-acting and less-potent cycloplegics in children. Nevertheless, cycloplegic refraction remains a gold standard to obtain the baseline refractive status of an eye and to negate the effect of accommodation despite associated difficulty to perform near work, photophobia and other adverse effects. 
In a typical pediatric eye clinic, a large number of ametropic children aged above 6 years have myopia ranging between -1 diopter sphere (DS) and -6 DS. Cycloplegic refraction in such a situation is routinely practiced. However, the practice of calling the patient back for a PMT may not be feasible or cost-effective especially if it does not add any further information that improves the final spectacle prescription. The autorefractometers are generally condemned for inducing the accommodation. However, autorefractometers such as Topcon RM 6000B use the technique of continuous fogging and hence it negates the accommodative urge giving more accurate readings even in the absence of cycloplegia. It is important to note that, in the present study we did not use the autorefraction without subjectively refining the sphere and cylinder obtained from the standard technique of subjective refraction (fogging, cross cylinder evaluation and a duochrome test). Previous investigators have reported good reproducibility with cycloplegic retinoscopy and cycloplegic autorefraction.  However, there may be little agreement between the two different objective refraction methods.  Hence, it is recommended to perform subjective refinement of the objective refraction whether obtained by autorefraction or retinoscopy. Despite employing the fogging and duochrome test in the study, we found that PMT and non-cycloplegic refraction tend to over-estimate a myopic refractive error. The mean difference between the cycloplegic and non-cycloplegic sphere was 0.4 (±0.7) and cylinder was 0.3 (±1.1). In keeping with the past study, in the present study, the cylinder axis did not vary significantly between both cycloplegic and non-cycloplegic refraction.  Ophthalmologists follow differing prescription guidelines for children; one group prescribes least correction in myopes (subjective refraction obtained under cycloplegic condition with red better response on duochrome test) while another group prescribes what patient subjectively accepts under non-cycloplegic correction. To whichever group the reader belongs to, as there was no significant difference in pre-cycloplegia refraction and PMT, both the groups do not need PMT. For the later group, they do not even need a cycloplegic refraction! In conclusion, a PMT is not warranted for prescribing spectacles in children with mild to moderate myopia.
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[Table 1], [Table 2]