SPECTACLE PRESCRIPTION VERIFICATION
SPECTACLE PRESCRIPTION ISO

The differences between the prescriptions written and actually dispensed in the two groups were analyzed using ‘z’ test for proportions. have shown that even small focal errors can create problems. We considered that an error of ≥0.50 D sphere or cylinder and >5 degree in cylinder axis would practically be significant enough to affect visual acuity and comfort. Our decision to use large tolerances will underestimate the dispensing error rate compared to the ANSI standards. We chose these tolerances arbitrarily because we did not find any Indian Standards for spectacle lens tolerances. Differences of ±≥0.50 D sphere or cylinder and >5 degree in cylinder axis were considered inaccurate. The spectacles were neutralized on lensometer (Vision Instruments, Ambala, India) by one author (KM). Spectacle prescriptions written were compared with prescription dispensed measured at next visit in both groups. Group 2 patients or their parents were enquired at next visit whether they actually asked the optician to verify the spectacles.

SPECTACLE PRESCRIPTION VERIFICATION

They were not instructed to observe the verification process.

Group 1 patients or their parents were not instructed regarding verification of the spectacles dispensed, whereas Group 2 patients or their parents were instructed that while collecting spectacles, they ask the optician to verify whether the spectacles have been dispensed as prescribed. Using random numbers, patients were distributed into Group 1 and Group 2 consisting of 100 patients in each. This prospective study, approved by our institutional review board, comprised of 200 patients who were prescribed spectacles at the Squint Centre, Chandigarh, India. The objectives of this study were to determine (1) how frequently the spectacle lenses are not dispensed as prescribed (2) which type of spectacle lenses (spherical or spherocylindrical) are more often dispensed inaccurately (3) in which element (power, axis or both power and axis) of lenses the error is commonly committed and (4) whether asking the optician to verify that the spectacle lenses have been dispensed as prescribed would decrease the frequency of inaccurate spectacles. To the best of our knowledge, there are no spectacle lens tolerances in India.

SPECTACLE PRESCRIPTION ISO

In UK, the most recent Europe-approved international standard BS EN ISO 21987: 2009 has recommended spectacle lens tolerances which are different from those in the ANSI Z80.1-2010. The most recently revised ANSI Z80.1-2010 approved the tolerances for spherical lens powers to ☐.13 diopters (D) for powers below ☖.50 D and ☒% for powers above ☖.50 D, the tolerances for cylindrical lens powers to ☐.13 D for powers ≤2.00 D, ☐.15 D for powers >2.00 to ≤4.50 D and ±4% for powers >4.50 D, and the tolerances for cylinder axis to ☑4° for powers ≤0.25 D, ☗° for powers >0.25 D to ≤0.50 D, ±5° for powers >0.50 D to ≤0.75 D, ☓° for powers >0.75 D to ≤1.50 D and ☒° for powers >1.50 D. In USA, the American National Standards Institute (ANSI) approved ophthalmic standards Z80 in 1964 and revised them from time to time. These tolerances vary from country to country. The tolerances for spectacle lenses are different for different parameters and different power ranges. To our knowledge, there is no report on this subject. It is, therefore, important to know whether the spectacles the patient is wearing have been dispensed as prescribed. Spectacles are also often prescribed for treatment of amblyopia and strabismus in young children. Accurate spectacles restore comfortable vision and enhance visual efficiency. Spectacles are the most widely practiced modality for the correction of refractive errors. To decrease the frequency of incorrect spectacles, the patients while collecting spectacles, should ask the optician to check whether the spectacles have been dispensed accurately. It is suggested that while prescribing spectacles, the patients should be made aware of the possibility of dispensing errors. These inaccuracies decreased significantly when patients while collecting spectacles, asked the optician to verify the accuracy of the spectacles dispensed. We found inaccurate spectacles in about one-third of our patients and incorrect spherocylinders more frequently with an error in the spherical element and cylinder axis. We investigated how frequently the spectacles are not dispensed as prescribed and whether the frequency of inaccurate spectacles would decrease if the patients, at the time of collecting spectacles, ask the optician to verify that the spectacles have been dispensed accurately. Spectacles are routinely prescribed by the ophthalmologist and dispensed by the opticians.