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Cycloplegic Refraction in Esotropic Children
Cycloplegic Refraction in Esotropic Children Cyciopentoiate versus Atropine ARTHUR L. ROSENBAUM, MD, J. BRONWYN BATEMAN, MD, DON L. BREMER, MD, P. Y. LIU, PhD Abstract: Retinoscopy was performed on a population of predominantly white esotropic children younger than 5.5 years with cyclopentolate 1% and atropine 1.0%. Atropine 1.0% revealed + 0.34 diopters more hyperopia than cyclopentolate 1.0%"when the mean differences between the two drugs were examined. Mean difference analysis would probably indicate that atropine retinoscopy was unnecessary. However, 22% of the children had + 1 .0 diopters or more of hyperopia uncovered by atropine. This significant subpopulation suggests that in young patients with esotropia, an atropine refraction is essential to uncover the maximum amount of hyperopia. Almost all of this subgroup with + 1 .00 or greater hyperopia had an initial cyclopentolate retinoscopy of + 2.00 diopters or more. Therefore, retinoscopy using atropine cycloplegia becomes even more important in this population. There was a trend for the greater differences to be in children older than age 2 years. However, these values were not statistically significant. [Key words: atropine, cyclopentolate, esotropia.] Ophthalmology 88: 1031-1 034, 1981
The relative accuracy of cycloplegic retinoscopy using cyclopentolate or atropine has remained a subject of debate for pediatric ophthalmologists. Atropine has been known to affect accommodative ability since the early reports of the herb belladonna.! Since the introduction of the concept of accommodative esotropia by Donders 2 in 1864, refraction under maximal pharmacologic cycloplegia has been an essential feature of the modern strabismic examination. Because atropine requires hours From the Department of Ophthalmology. Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles. Presented at the Eighty-Fifth Annual Meeting of the American Academy of Ophthalmology, Chicago, November 2-7, 1980. Supported in part by Grant S770712 from Research to Prevent Blindness, Inc. Reprint requests to Arthur L. Rosenbaum, MD, Jules Stein Eye Institute, Los Angeles, CA 90024. 0161-6420/81/1000/10311$00.70
for maximum cycloplegia, the traditional technique for an atropine retinoscopic examination has been to instill the drug in the conjunctival sac three times a day for three days prior to the examination. 3 Cyclopentolate, which requires only 30 to 60 minutes for maximum cycloplegia, is a convenient drug for office retinoscopic examinations. 4,5 The rapidity with which a clinician may perform cycloplegic retinoscopic examinations with cyclopentolate makes this drug an attractive agent in a busy ophthalmic practice. Studies on older children and adults indicate comparable cycloplegic abilities with atropine and cyclopentolate. 6 - 8 However, in the young esotropic patient, maximum cycloplegia is essential as these children have powerful accommodative ability and require accurate retinoscopy. Therefore, this study was undertaken to compare the cycloplegic abilities of the two drugs in esotropic children younger than six years of age.
© American Academy of Ophthalmology
1031
OPHTHALMOLOGY • OCTOBER 1981 • VOLUME 88 • NUMBER 10
tients. Blue iris included green coloration and brown iris included hazel coloration.
MATERIALS AND METHODS A .total of 120 esotropic patients (240 eyes) were studIed. The population included 66 (55%) females and 54 (45 %) males. The patients ranged in age from three months to six years with the median age of the entire sample being 2.3 years. Five patients had brown skin color. Iris coloration of the initial 53 patients was blue in 25 (47%) patients and brown in 28 (53%) patients. All refractive errors were expressed as the spherical equivalent for data analysis. Th~ study population was prospectively limited to chIldren wIth esotropic deviations ranging in age from newborn infants up to six-year-old children who had not undergone any surgical procedures. !~e. patients. were included consecutively from all ImtIal examInations performed by the authors. Patients with paretic strabismus or syndromal identification. were no~ included. A history of prior cyclople?IC refractIOns or the presence of previously prescrIbed glasses did not eliminate a patient from the study. On the initial visit, patients received dilation with cyclopentolate, two drops to each eye, with a five-minute interval between drops. For infants younger than one year, cyclopentolate 0.5% was used; for children between the ages of one and six years, cyclopentolate 1.0% was used. Retinoscopy was performed between 45 and 60 minutes after the first drop, and the results were recorded. Two to three weeks later, the parents administered atropine, in the form of ointment or solution, to both eyes of the patient, morning, noon, and evening for three days prior to the refraction. For infants younger than one year, atropine 0.5% was administere.d, and for children between the ages of one and SIX years, atropine 1.0% was administered. If an infan~ younge.r than one year of age developed an atropIne reactIOn, fever, or flushing of the face this dosage was stopped and the process was re~ peated with atropine 0.25% in oil. If a child betwee~ the age~ of one and six years developed an atrop~ne reactIOn, the process was repeated with atropIne 0.5 %. Retinoscopy was performed on the second visit by the same individual who recorded the cyclopentolate refraction. The records were not insp~c.ted prio~ to the retinoscopy of the patient reCeIVIng atropIne. Age, sex, and race were recorded for all pa-
RESULTS The retinoscopic results with both drugs are summarized in Tables lA and lB. Cyclopentolate un~overed ~ mean of + 2.43 diopters of hyperopia ~hIle atropIne revealed + 2.77 diopters, for a mean dIfference of + 0.34 diopter. This difference is stati~tically ~ignificant (P < 0.01). There was no sigmficant dIfference between the right and left eyes with either drug. Of the 120 patients, 26 (22 %) had a difference of + 1 .00 diopter or more between the cyclopentolate and atropine refractions in at least one eye. Twenty-one of these 26 patients with a difference of + 1.00 diopter or more between the two drugs had an initial cyclopentolate refraction of + 2.00 or more diopters in that eye, while only 5 of the 26 had an initial cyclopentolate refraction less than + 2.00 diopters. Fifty-three of 94 patients who had less than + 1 .00 diopter difference betw~en the two drugs had an initial cyclopentolate retInoscopy of + 2.00 diopters or more. This difference in initial cyclopentolate refraction is statistically significant (P < 0.025) (Table 2). Of the 26 patients with + 1 .00 diopter difference, 18 were two years of age or older and eight were younger than two years of age. Fifty-five of 94 patients with a difference of less than + 1.00 d~opter we!e two years of age or older. This age dIfference IS not statistically significant (P > 0.05) (Table 3). Regression analysis was performed on the first 53 patients to assess the relationship between the atropine and cyclopentolate retinoscopy findings and eye color. The results indicate that eye color Table 1A. Cycloplegic Retinoscopic Results Converted to Spherical Equivalents (N = 240 Eyes) Retinoscopy Cyclopentolate right eye left eye Atropine right eye left eye
Range (diopters)
Mean (diopters)
- 3.50 to + 10.25
+2.42
-9.75to +11.00
+2.44
-3.50 to + 10.25 -9.75to +10.75
+2.78 +2.76
Table 1B. Atropine Retinoscopy Minus Cyclopentolate Retinoscopy
Right Eye Left Eye
1032
Number of Eyes Examined
Range (diopters)
Mean (diopters)
Standard Deviation
240 240
- 2.00 to + 3.00 - 2.00 to + 2.37
+ 0.35 + 0.32
±0.63 +0.60
ROSENBAUM, et al.• CYCLOPENTOLATE VERSUS ATROPINE
Table 2. Retinoscopic Differences (Atropine Minus Cyclopentolate) (N = 120) Initial Cyclopentolate Retinoscopy +2.00 diopters or more Less than + 2.00 diopters
Differences + 1.00 Diopter or More
Less Than + 1.00 Diopter
21
53
5
41
Table 3. Retinoscopic Differences (Atropine Minus Cyclopentolate) Differences Age of Patients 2 to 6 years Less than 2 years
+ 1.00 Diopter or More
Less Than + 1.00 Diopter
18 8
55 39
had no effect on either the atropine or cyclopentolate retinoscopy.
COMMENTS This study compares the ability of cyclopentolate and atropine to uncover maximum hyperopic refractive error in esotropic children younger than age six years. Our data indicate that, in the total population studied, atropine effectively uncovered + 0.34 diopter more hyperopia than was uncovered by cyclopentolate. This mean difference parallels a similar study by Robb and Peterson. 9 They found that atropine uncovered from 0.33 to 0.5 diopter more hyperopia than cyclopentolate 1.0% in esotropic children younger than six years of age. Ingram and Barr have found cyclopentolate to be significantly less effective than atropine in producing cycloplegia in one-year-old children. 10 While statistically this difference is highly significant, clinically, it is of little importance when only the mean differences of hyperopia are examined. A comparison of mean differences between the two drugs masks the clinically important findings that atropine revealed + 1.00 or more diopters of hyperopia in at least one eye of 22% of the study group. This is statistically significant (P < 0.05). To characterize this subpopulation, it appears that almost all children who showed + 1.00 diopter or more difference of hyperopia with atropine 1.0% compared with cyclopentolate 1.0% had initial cyclopentolate retinoscopy values of + 2.00 diopters or more. This supports the clinical impression that atropine is more effective than cyclopentolate in revealing hyperopia when greater amounts of hyperopia are present. 11 No striking difference in residual accommoda-
tion between the two drugs is apparent in earlier studies. Residual accommodation after the use of cyclopentolate is reported to be between 1.25 and 2.50 diopters in a general population of older children and adults.6-8.12-14 It may be even greater in black patients. 15 - 17 Residual accommodation with atropine is approximately 2.0 diopters in a similar population,a,ls but these studies are of older patients and make no distinction between the young esotropic patient and the rest of the population. 19 The patient popUlation in this study was limited to esotropic children younger than six years of age. This is the group with the highest accommodative ability, in whom an accurate cycloplegic refraction is most essential. This study was based on retinoscopic findings, since it is not feasible to assess residual accommodation in young children. To minimize the number of overall visits, the cyclopentolate retinoscopy was performed on the first visit and atropine examination on the second. Thus; although our study is not double-blind, neither examiner knew the results of the previous cyclopentolate retinoscopy. It is preferable to reduce the angle of esotropia as soon as possible by correcting the maximal amount of hyperopia initially. Although neither drug produces total cycloplegia, we recommend the use of atropine on all esotropic children in which the initial cyclopentolate refraction is + 2.00 diopters or greater. Additionally, we recommend that refractions be repeated periodically in an attempt to uncover the maximum hyperopia. The more the esotropia is reduced, the greater the chance is to preserve or regain fusional ability in the acquired-esotropic patient. Also, the chance for continued contracture of the medial rectus muscle and the development of a non-accommodative component of the esotropia may be lessened. Finally, atropine cycloplegia in infants with congenital esotropia may result initially in the discovery of significant hyperopia and suggest spectacle correction rather than immediate surgery. This may aid in the ultimate reduction of surgical overcorrection.
REFERENCES 1. Wells WC. Observations and experiments on vision. Phil Trans R Soc Lond 1811; 101 :378-91. 2. Donders FC. On the Anomalies of Accommodation and Refraction of the Eye, with a Preliminary Essay on Physiological Dioptics, translated by WO. Moore. London: The New Sydenham Society, 1864. 3. Marron J. Cycloplegia and mydriasis by use of atropine, scopolamine and homatropineparedrine. Arch Ophthalmol 1940; 23:340-50. 4. Milder B, Riffenburgh RS. An evaluation of cyclogyl (compound 75 G.T.). Am J Ophthalmol 1953; 36: 1724-6.
1033
OPHTHALMOLOGY. OCTOBER 1981 • VOLUME 88 • NUMBER 10 5. Parks MM. Ocular Motility and Strabismus. New York: Harper and Row, 1975. 6. Gettes BC. Dibutoline sulfate: comparative clinical study of cycloplegic effect. Arch Ophthalmol 1950; 43:446-53. 7. Milder B. Tropicamide as a cycloplegic agent. Arch Ophthalmol 1961; 66:70-2 8. Prangen AD. What constitutes satisfactory cycloplegia . Am J Ophthalmol1931 ; 14:665-71 . 9 . Robb RM, Petersen RA . Cycloplegic refractions in children . J Pediatr Ophthalmol1968 ; 5:1 10-14. 10. Ingram RM, Barr A. Refraction of 1-year-old children after cycloplegia with 1% cyclopentolate: comparison with findings after atropinisation. Br J Ophthalmol 1979; 63:348- 52. 11. Apt L. Personal communication . 12. Cher I. Experiences with cyclogyl. Trans Ophthalmol Soc UK 1959; 79:665-70.
1034
13. Duane A. Subnormal accommodation. Arch Ophthalmol 1925; 54:566-87. 14. Priestley BS, Medine MM. A new mydriatic and cycloplegic drug: compound 75 G.T. Am J Ophthalmol 1951; 34:572-5. 15. Gettes BC. Three new cycloplegic drugs: clinical report. Arch Ophthalmol 1954; 51 :467-72. 16. Gettes BC, Belmont O. Tropicamide: comparative cycloplegic effects. Arch Ophthalmol 1961; 66:336-40. 17. Gettes BC , Leopold IH. Evaluation of five new cycloplegic drugs. Arch Ophthalmol 1953 ; 49:24-7 . 18. Wolf AV, Hodge HC. Effects of atropine sulfate, methylatropine nitrate (methropine) and homatropine hydrobromide on adult human eyes. Arch Ophthalmol 1946; 36:293-301. 19. Barbee RF, Smith WO Jr. A comparative study of mydriatic and cycloplegic agents; in human subjects without eye disease. Am J Ophthalmol 1957; 44:617-22.
The relative accuracy of cycloplegic retinoscopy using cyclopentolate or atropine has remained a subject of debate for pediatric ophthalmologists. Atropine has been known to affect accommodative ability since the early reports of the herb belladonna.! Since the introduction of the concept of accommodative esotropia by Donders 2 in 1864, refraction under maximal pharmacologic cycloplegia has been an essential feature of the modern strabismic examination. Because atropine requires hours From the Department of Ophthalmology. Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles. Presented at the Eighty-Fifth Annual Meeting of the American Academy of Ophthalmology, Chicago, November 2-7, 1980. Supported in part by Grant S770712 from Research to Prevent Blindness, Inc. Reprint requests to Arthur L. Rosenbaum, MD, Jules Stein Eye Institute, Los Angeles, CA 90024. 0161-6420/81/1000/10311$00.70
for maximum cycloplegia, the traditional technique for an atropine retinoscopic examination has been to instill the drug in the conjunctival sac three times a day for three days prior to the examination. 3 Cyclopentolate, which requires only 30 to 60 minutes for maximum cycloplegia, is a convenient drug for office retinoscopic examinations. 4,5 The rapidity with which a clinician may perform cycloplegic retinoscopic examinations with cyclopentolate makes this drug an attractive agent in a busy ophthalmic practice. Studies on older children and adults indicate comparable cycloplegic abilities with atropine and cyclopentolate. 6 - 8 However, in the young esotropic patient, maximum cycloplegia is essential as these children have powerful accommodative ability and require accurate retinoscopy. Therefore, this study was undertaken to compare the cycloplegic abilities of the two drugs in esotropic children younger than six years of age.
© American Academy of Ophthalmology
1031
OPHTHALMOLOGY • OCTOBER 1981 • VOLUME 88 • NUMBER 10
tients. Blue iris included green coloration and brown iris included hazel coloration.
MATERIALS AND METHODS A .total of 120 esotropic patients (240 eyes) were studIed. The population included 66 (55%) females and 54 (45 %) males. The patients ranged in age from three months to six years with the median age of the entire sample being 2.3 years. Five patients had brown skin color. Iris coloration of the initial 53 patients was blue in 25 (47%) patients and brown in 28 (53%) patients. All refractive errors were expressed as the spherical equivalent for data analysis. Th~ study population was prospectively limited to chIldren wIth esotropic deviations ranging in age from newborn infants up to six-year-old children who had not undergone any surgical procedures. !~e. patients. were included consecutively from all ImtIal examInations performed by the authors. Patients with paretic strabismus or syndromal identification. were no~ included. A history of prior cyclople?IC refractIOns or the presence of previously prescrIbed glasses did not eliminate a patient from the study. On the initial visit, patients received dilation with cyclopentolate, two drops to each eye, with a five-minute interval between drops. For infants younger than one year, cyclopentolate 0.5% was used; for children between the ages of one and six years, cyclopentolate 1.0% was used. Retinoscopy was performed between 45 and 60 minutes after the first drop, and the results were recorded. Two to three weeks later, the parents administered atropine, in the form of ointment or solution, to both eyes of the patient, morning, noon, and evening for three days prior to the refraction. For infants younger than one year, atropine 0.5% was administere.d, and for children between the ages of one and SIX years, atropine 1.0% was administered. If an infan~ younge.r than one year of age developed an atropIne reactIOn, fever, or flushing of the face this dosage was stopped and the process was re~ peated with atropine 0.25% in oil. If a child betwee~ the age~ of one and six years developed an atrop~ne reactIOn, the process was repeated with atropIne 0.5 %. Retinoscopy was performed on the second visit by the same individual who recorded the cyclopentolate refraction. The records were not insp~c.ted prio~ to the retinoscopy of the patient reCeIVIng atropIne. Age, sex, and race were recorded for all pa-
RESULTS The retinoscopic results with both drugs are summarized in Tables lA and lB. Cyclopentolate un~overed ~ mean of + 2.43 diopters of hyperopia ~hIle atropIne revealed + 2.77 diopters, for a mean dIfference of + 0.34 diopter. This difference is stati~tically ~ignificant (P < 0.01). There was no sigmficant dIfference between the right and left eyes with either drug. Of the 120 patients, 26 (22 %) had a difference of + 1 .00 diopter or more between the cyclopentolate and atropine refractions in at least one eye. Twenty-one of these 26 patients with a difference of + 1.00 diopter or more between the two drugs had an initial cyclopentolate refraction of + 2.00 or more diopters in that eye, while only 5 of the 26 had an initial cyclopentolate refraction less than + 2.00 diopters. Fifty-three of 94 patients who had less than + 1 .00 diopter difference betw~en the two drugs had an initial cyclopentolate retInoscopy of + 2.00 diopters or more. This difference in initial cyclopentolate refraction is statistically significant (P < 0.025) (Table 2). Of the 26 patients with + 1 .00 diopter difference, 18 were two years of age or older and eight were younger than two years of age. Fifty-five of 94 patients with a difference of less than + 1.00 d~opter we!e two years of age or older. This age dIfference IS not statistically significant (P > 0.05) (Table 3). Regression analysis was performed on the first 53 patients to assess the relationship between the atropine and cyclopentolate retinoscopy findings and eye color. The results indicate that eye color Table 1A. Cycloplegic Retinoscopic Results Converted to Spherical Equivalents (N = 240 Eyes) Retinoscopy Cyclopentolate right eye left eye Atropine right eye left eye
Range (diopters)
Mean (diopters)
- 3.50 to + 10.25
+2.42
-9.75to +11.00
+2.44
-3.50 to + 10.25 -9.75to +10.75
+2.78 +2.76
Table 1B. Atropine Retinoscopy Minus Cyclopentolate Retinoscopy
Right Eye Left Eye
1032
Number of Eyes Examined
Range (diopters)
Mean (diopters)
Standard Deviation
240 240
- 2.00 to + 3.00 - 2.00 to + 2.37
+ 0.35 + 0.32
±0.63 +0.60
ROSENBAUM, et al.• CYCLOPENTOLATE VERSUS ATROPINE
Table 2. Retinoscopic Differences (Atropine Minus Cyclopentolate) (N = 120) Initial Cyclopentolate Retinoscopy +2.00 diopters or more Less than + 2.00 diopters
Differences + 1.00 Diopter or More
Less Than + 1.00 Diopter
21
53
5
41
Table 3. Retinoscopic Differences (Atropine Minus Cyclopentolate) Differences Age of Patients 2 to 6 years Less than 2 years
+ 1.00 Diopter or More
Less Than + 1.00 Diopter
18 8
55 39
had no effect on either the atropine or cyclopentolate retinoscopy.
COMMENTS This study compares the ability of cyclopentolate and atropine to uncover maximum hyperopic refractive error in esotropic children younger than age six years. Our data indicate that, in the total population studied, atropine effectively uncovered + 0.34 diopter more hyperopia than was uncovered by cyclopentolate. This mean difference parallels a similar study by Robb and Peterson. 9 They found that atropine uncovered from 0.33 to 0.5 diopter more hyperopia than cyclopentolate 1.0% in esotropic children younger than six years of age. Ingram and Barr have found cyclopentolate to be significantly less effective than atropine in producing cycloplegia in one-year-old children. 10 While statistically this difference is highly significant, clinically, it is of little importance when only the mean differences of hyperopia are examined. A comparison of mean differences between the two drugs masks the clinically important findings that atropine revealed + 1.00 or more diopters of hyperopia in at least one eye of 22% of the study group. This is statistically significant (P < 0.05). To characterize this subpopulation, it appears that almost all children who showed + 1.00 diopter or more difference of hyperopia with atropine 1.0% compared with cyclopentolate 1.0% had initial cyclopentolate retinoscopy values of + 2.00 diopters or more. This supports the clinical impression that atropine is more effective than cyclopentolate in revealing hyperopia when greater amounts of hyperopia are present. 11 No striking difference in residual accommoda-
tion between the two drugs is apparent in earlier studies. Residual accommodation after the use of cyclopentolate is reported to be between 1.25 and 2.50 diopters in a general population of older children and adults.6-8.12-14 It may be even greater in black patients. 15 - 17 Residual accommodation with atropine is approximately 2.0 diopters in a similar population,a,ls but these studies are of older patients and make no distinction between the young esotropic patient and the rest of the population. 19 The patient popUlation in this study was limited to esotropic children younger than six years of age. This is the group with the highest accommodative ability, in whom an accurate cycloplegic refraction is most essential. This study was based on retinoscopic findings, since it is not feasible to assess residual accommodation in young children. To minimize the number of overall visits, the cyclopentolate retinoscopy was performed on the first visit and atropine examination on the second. Thus; although our study is not double-blind, neither examiner knew the results of the previous cyclopentolate retinoscopy. It is preferable to reduce the angle of esotropia as soon as possible by correcting the maximal amount of hyperopia initially. Although neither drug produces total cycloplegia, we recommend the use of atropine on all esotropic children in which the initial cyclopentolate refraction is + 2.00 diopters or greater. Additionally, we recommend that refractions be repeated periodically in an attempt to uncover the maximum hyperopia. The more the esotropia is reduced, the greater the chance is to preserve or regain fusional ability in the acquired-esotropic patient. Also, the chance for continued contracture of the medial rectus muscle and the development of a non-accommodative component of the esotropia may be lessened. Finally, atropine cycloplegia in infants with congenital esotropia may result initially in the discovery of significant hyperopia and suggest spectacle correction rather than immediate surgery. This may aid in the ultimate reduction of surgical overcorrection.
REFERENCES 1. Wells WC. Observations and experiments on vision. Phil Trans R Soc Lond 1811; 101 :378-91. 2. Donders FC. On the Anomalies of Accommodation and Refraction of the Eye, with a Preliminary Essay on Physiological Dioptics, translated by WO. Moore. London: The New Sydenham Society, 1864. 3. Marron J. Cycloplegia and mydriasis by use of atropine, scopolamine and homatropineparedrine. Arch Ophthalmol 1940; 23:340-50. 4. Milder B, Riffenburgh RS. An evaluation of cyclogyl (compound 75 G.T.). Am J Ophthalmol 1953; 36: 1724-6.
1033
OPHTHALMOLOGY. OCTOBER 1981 • VOLUME 88 • NUMBER 10 5. Parks MM. Ocular Motility and Strabismus. New York: Harper and Row, 1975. 6. Gettes BC. Dibutoline sulfate: comparative clinical study of cycloplegic effect. Arch Ophthalmol 1950; 43:446-53. 7. Milder B. Tropicamide as a cycloplegic agent. Arch Ophthalmol 1961; 66:70-2 8. Prangen AD. What constitutes satisfactory cycloplegia . Am J Ophthalmol1931 ; 14:665-71 . 9 . Robb RM, Petersen RA . Cycloplegic refractions in children . J Pediatr Ophthalmol1968 ; 5:1 10-14. 10. Ingram RM, Barr A. Refraction of 1-year-old children after cycloplegia with 1% cyclopentolate: comparison with findings after atropinisation. Br J Ophthalmol 1979; 63:348- 52. 11. Apt L. Personal communication . 12. Cher I. Experiences with cyclogyl. Trans Ophthalmol Soc UK 1959; 79:665-70.
1034
13. Duane A. Subnormal accommodation. Arch Ophthalmol 1925; 54:566-87. 14. Priestley BS, Medine MM. A new mydriatic and cycloplegic drug: compound 75 G.T. Am J Ophthalmol 1951; 34:572-5. 15. Gettes BC. Three new cycloplegic drugs: clinical report. Arch Ophthalmol 1954; 51 :467-72. 16. Gettes BC, Belmont O. Tropicamide: comparative cycloplegic effects. Arch Ophthalmol 1961; 66:336-40. 17. Gettes BC , Leopold IH. Evaluation of five new cycloplegic drugs. Arch Ophthalmol 1953 ; 49:24-7 . 18. Wolf AV, Hodge HC. Effects of atropine sulfate, methylatropine nitrate (methropine) and homatropine hydrobromide on adult human eyes. Arch Ophthalmol 1946; 36:293-301. 19. Barbee RF, Smith WO Jr. A comparative study of mydriatic and cycloplegic agents; in human subjects without eye disease. Am J Ophthalmol 1957; 44:617-22.