The use of neutral density filters in PlusoptiX devices.

The software of the PlustoptiX devices is developed for pupils up to 7.8 to 8mm in size. In the study “a double blind randomized study on the efficacy of cyclopentolate 1% and tropicamide 1% in children (MEC nr NL32954.098 /1010-077; NTR 2476), pupil sizes will be over 8mm in a considerable amount of cases. To avoid drop-out neutral density filters are used to decrease light intensity. This study will investigate the validity of the use of neutral density. Further the optimal filter will be determined.

The software of the PlustoptiX devices is developed for pupils up to 7.8 to 8mm in size. In the study “a double blind randomized study on the efficacy of cyclopentolate 1% and tropicamide 1% in children (MEC nr NL32954.098 /1010-077; NTR 2476), pupil sizes will be over 8mm in a considerable amount of cases. To avoid drop-out neutral density filters are used to decrease light intensity. This study will investigate the validity of the use of neutral density. Further the optimal filter will be determined.

For both protocols: To prevent differences in pupil dynamics eligible subjects will be adapted to the room light for 5 minutes. During this time the purpose of the measurements will be explained, time investment (3 minutes) be discussed and oral consent asked. After consent measurements will be made. Success (data) or failure (no data) will be recorded. Pupil size, sfere, cylinder and axes of each measurement will be noted. Refractive outcomes will be converted in SEQ.



For the un-dilated protocol the measurements will be made in consecutive order; entry measurements without glasses, measurements with glasses, measurements with glasses and filter 91% etc.



For the dilated protocol the measurements will take place 35 minutes after application of the cycloplegics. The refractive state of the subject will be assessed with the Retinomax K-plus 3. The values found will be placed in a trial frame. Measurements will be made in consecutive order; entry measurements without trail glasses, measurements with trial glasses, measurements with trail glasses and filter 91% etc.

Measurements are made with the Powerrefractor II; software installed of the PlustoptiX A09. Both for the un- and dilated: A entry measurement with and without glasses will be made. Thereafter three measurements will be made with glasses and consecutive neutral density filters. Five different absorptive neutral density filters will be used; 91% (Newport Ltd), 79% (Newport Ltd), 62% (Thorlabs Ltd), 46% (Thorlabs Ltd) and 34% (Thorlabs Ltd).