Eye (1989) 3, 845-848
Pupil Dilatation with Tropicamide. The Effects on Acuity, Accommodation and Refraction
D. M. I. MONTGOMERY! and C. J. MACEWANZ Glasgow and Dundee.
Summary The effect of pupil dilatation with tropicamide 1 % on visual acuity and accommo dation was assessed in 100 eyes of 52 consecutive patients attending the general ophthalmic outpatient clinic. Snellen visual acuity remained unchanged in 55 eyes and deteriorated by one line in 41 eyes. The remaining four eyes deteriorated by two lines. Tropicamide gave rise to a reduction in the amplitude of accommodation which tended to vary inversely with the age of the patient. However, all patients who wore reading glasses for presbyopia were still able to read when their pupils had been dilated.
Many drugs are used routinely in ophthalmic acuity and accommodation in such a practice to dilate the pupil for adequate exam population. ination of the ocular fundus. Selection may be based on the speed of onset and duration of action of the drug as well as on the presence Materials and methods and severity of any unwanted effects such as Tropicamide 1 % was used to dilate the pupils cycloplegia. Tropicamide is a drug often of 100 eyes of 52 consecutive patients who favoured because of its short duration of required fundoscopy during attendance at the action and relatively greater mydriatic than general ophthalmology outpatient clinic. The cycloplegic effect. mean patient age was 38 years (range 6-84 Concern is often expressed with regard to years). Prior to dilatation retinoscopy was adverse effects of pupil dilatation on vision carried out and the uncorrected and best cor which might affect patients' ability to travel rected visual acuities were recorded using a home safely or to return to work. Tropicamide standard six metre Snellen chart. The ampli has recently been shown to have little effect tude of accommodation was measured for on the distance visual acuity of a group of each eye using the RAF rule. One drop of healthy young volunteers.! However, no tropicamide 1 % was instilled into each eye attempt �as hitherto been made to quantify producing sufficient dilatation in all cases for visual impairment associated with pupil satisfactory examination after thirty minutes. dilatation in the, often elderly, clinic popula At this time, the uncorrected and corrected tion. The aim of this study was to determine acuities were again recorded. Retinoscopy the effect of tropicamide dilatation on visual was repeated and any change in refraction was
From:! Registrar in Ophthalmology, Tennent Institute of Ophthalmology, Western Infirmary, Glasgow. 2Senior Registrar in Ophthalmology, Eye Department. Ninewells Hospital, Dundee.
Correspondence to: Dr DMI Montgomery, Tennent Institute of Ophthalmology, Western Infirmary, Glasgow Gll 6NT. 846 D. M. I. MONTGOMERY ANDC. 1. MACEWAN noted. The amplitude of accommodation was lines of Snellen acuity (Fig.1 ) . There was no again measured. significant difference between the results Eyes were grouped according to their obtained for hypermetropes, myopes or refractive state namely emmetropes (33 eyes), emmetropes (X2 test; 0.1
Key 0 Hyperm.t�
.. Emmetrope f:::.CORRECTED , Myope 1:::. VISUAL ACUITY UNCORRECTED 0 lLinu 5n.. lenl VISUAL ACUITY Key Hypermetrope (Un" SneUenl • Myope
.. Emm.t�
- .. m�x x-�:1�:� _�!tj8&__ Moo o---l�iM__ QOOOo-OOOO 1 -10 11-20 21-30 31-.40 41-50 51-60 61-70 71-80 81-90 1-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90
AGE (YEARSI AGEIYEARS) Fig. 1 Fig. 2
fl ACCOMMOOAT1ON IOIOPTRESI Key 0 H)1)«m.tropt
.M_ .. ElTlm.lr�
...... 00 0000 "0 ....00 0 __.:::. . �� ��-=.'W'=. :";' ______� L- 11-20 21-30 51-60 61-70 71-80 81-90 AGE IYEARSI Fig. 3 Fig. 4 PUPIL DILATATION WITH TROPICAMIDE 847
'" ACCOMODATlON off after one hour.4.5 Although it has been IOIOPRESI suggested that the 1 % solution offers no advantage over the 0.5% solution for dilata tion5 we used the 1 % solution to demonstrate IS the maximum effect of the drug after only one drop. The examination began at 30 minutes to coincide with the time of maximum drug action. 10 Theoretically, the instillation of trop icamide might be expected to impair vision by two main mechanisms. Firstly, mydriasis .. might make manifest a refractive error pre ... viously masked by the stenopaeic effect of a
... small pupil. The depth of fieldwill be reduced o. while spherical aberration and glare may be introduced. Secondly, the documented cycloplegic effect of tropicamide,3,4,5,1,8 by reducing accommodation, could impair near
/::; CORRECTED VISUAL ACUITY IUNES SNEllENI vision in all patients except uncorrected myo pes who do not require accommodation for Fig. 5 near vision. Moreover latent hypermetropia may be made manifest resulting in impaired before the administration of tropicamide was distance acuity. six dioptres (range 1-20) and after trop In practice, we found that tropicamide 1 %, icamide was three dioptres (range 0.5-7). The while producing pupillary dilatation adequate change in accommodation tended to vary for fundoscopy, caused little visual disturb inversely with age (Fig.4). Twenty nine ance as assessed by the methods described. patients wore reading glasses for presbyopia This may reflect the rather variable and and none found difficulty with reading follow incomplete cycloplegia produced by a single ing the instillation of tropicamide. Only 14 drop of this drug. patients were rendered unable to read at a Corrected visual acuity in particular was comfortable distance. The change in accom unaffected in the great majority of patients. modation was unrelated to the change in dis Those who did suffer an impairment in acuity tance acuity (Fig.5). would not have been predicted on the basis of either age or the refractive state of the eyes. Refraction Uncorrected acuity also showed little The retinoscopy readings remained unaltered difference between the pre- and post-dilata in 83 eyes, increased by one dioptre in ten eyes tion levels. This assessment was included as and by 1 to 3 dioptres in the remaining seven patients may arrive at a clinic without glasses eyes. All patients in the last group were under and suffer a reduction in vision due to a pre the age of 25 years. Only eight of the 16 chil viously masked refractive error. One patient dren under the age of ten years demonstrated in this study did suffer a significant reduction any change in retinoscopy. in uncorrected acuity in one eye, falling from 6/12 to 6/60. This was a young hypermetropic Discussion man who had with the rule astigmatism (the Tropicamide, a parasympatholytic agent, is fellow eye being amblyopic) and he illustrates widely used for pupil dilatation because of its that some patients may be diminishing the rapid onset and short duration of action. This effect of their refractive error by means of effect takes approximately 30 minutes to accommodation or a small pupil. become fully effective, stays at its peak for The uncorrected acuity of emmetropes was another 10-20 minutes and lasts up to four more affected than that of hypermetropes or hours.3 Its cycloplegic action has largely worn myopes. This can be explained on the basis 848 D.M. 1.MONTGOMERY AND C. J. MACEWAN that the emmetropes initially had better acu in predicting such disability. For this reason it ities. Sixty-three per cent of eyes with a refrac is recommended that while the doctor may tive error had an initial acuity of 6/18 or worse readily advise his patient of the likelihood of compared with 6/5 in some of the emmetropes visual disturbance following pupil dilatation, and were therefore less sensitive to smaller in any individual case the onus of respon increments on the Snellen chart (eg 6/36 to sibility for his own safety, and the safety of 6/60 compared with 6/5 to 6/6). others, must remain with the patient whose subjective assessment of any form of visual The change in accommodation was noted to impairment is likely to be ultimately the most vary inversely with the age of the patients, sensitive indicator of risk to driving and other reflecting the reduced residual accommo abilities. dation associated with ageing. It should be remembered, however, that some apparent We wish to thank Professor W. S. Foulds for his loss of amplitude of accommodation may be encouragement and helpful criticism of this work and Dr D. Allen for his assistance with the statistical due to loss of depth of fieldasssociated with a analysis. large pupillary aperture. This may explain the References discrepancy between the retinoscopic findings 1 Nelson ME and Orton HP: Counteracting the Effects and the accommodation measurements as of Mydriatics. Does it benefit the patient? Arch well as the lack of correlation between the Ophthalmol1987, 105: 486-9. changes in distance acuity and 2 Rosner B: Statistical methods in ophthalmology: an accommodation. adjustment for the interclass correlation between eyes. Biome trics 1982,38: 105-14. In conclusion, it should be pointed out that 3 Hiatt RL and Jerkins G: Comparisons of Atropine while the clinical tests of visual function and Tropicamide in Esotropia. Ann Ophthalmol employed in this study are useful indicators of 1983,4: 341-3. the level of potential subjective difficulties for 4 Milder B: Tropicamide as a Cycloplegic Agent. Arch Ophthalmol1961,4: 341-3. the patient they should not be regarded as 5 Gettes BC and Belmont 0: Tropicamide: Compara foolproof. For example, a patient with early tive Cycloplegic Effects. Arch Ophthalmol1961, lens opacities may achieve 6/9 acuity with dil 66: 70-4. ated pupils in the subdued lighting of the clinic 6 Davidson SI: Mydriatic and Cycloplegic Drugs. but be quite incapacitated by glare on entering Trans OphthalmolSoc UK 1976, 96: 327-9. 7 Gettes BC: Three New Cycloplegic Drugs. Arch bright sunlight. It is unlikely that more sophis Ophthalmol1954, 51: 467-72. ticated visual assessment, such as contrast 8 Gettes BC: Tropicamide: A New Cycloplegic sensitivity testing, would be any more reliable Mydriatic. Arch OphthalmoI1961, 65: 48-51.