title: Does astigmatism alter with cycloplegia?
abstract: OBJECTIVE
  To determine the effect of the cyclopentolate 1% on the cylindrical and spherical components of the refraction.
  
  
  METHODS
  Three hundred seventy-five eyes of 195 subjects, including 74 males and 121 females, aged from 3 to 59 years were refracted before and 30 min after cyclopentolate 1% eye drop instillation. To compare cylindrical data, power vector analysis (J0 and J45 cross cylinder) was applied.
  
  
  RESULTS
  A statistically significant difference between the J0 values of the noncycloplegic and cycloplegic refraction was revealed (P = 0.006) while the J45 values did not significantly differ. 95% limit of agreement for dry and cycloplegic values of the J0 and J45 were -0.22 to 0.25 and -0.19 to 0.20, respectively. Astigmatism difference was separately analyzed in emmetropic, myopic and hyperopic eyes. The J0 difference was significant (P = 0.014) only in hyperopic eyes. Spherical equivalent (SE) values in cycloplegic refraction were significantly more hyperopic than those yielded in dry refraction by mean difference of +1.16 ± 1.20 diopters (P < 0.0001). Spherical equivalent difference (SED) values were negatively correlated with age.
  
  
  CONCLUSIONS
  Our findings indicated that cycloplegic drops caused a statistically significant shift in the "with the rule" and "against the rule" astigmatisms, although the oblique astigmatisms remained unaffected. Further research with larger sample sizes are needed to answer what mechanisms are involved in changing cylinder with cycloplegia.
authors: Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
authors: Amir
authors: A
authors: Asharlous
authors: Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran; Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
authors: Hassan
authors: H
authors: Hashemi
authors: Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
authors: Ebrahim
authors: E
authors: Jafarzadehpur
authors: Department of Optometry, Iran University of Medical Sciences, Tehran, Iran.
authors: Ali
authors: A
authors: Mirzajani
authors: Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
authors: Abbasali
authors: A
authors: Yekta
authors: Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
authors: Payam
authors: P
authors: Nabovati
authors: Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors: Mehdi
authors: M
authors: Khabazkhoob
keywords: Agreement; Astigmatism; Cycloplegia; Noncycloplegia