Nyctometry
Nyctometry
Nyctometry is one of the diagnostic methods in ophthalmology, used for testing mesopic vision - vision in the dark. This type of vision is located between the photopic vision (seeing under ordinary daylight ensured by the sensory cells of the retinal cones) and scotopic vision (seeing in the dark, ensured by the rods). Rods also allow fine resolution of various degrees of lightness.
Nyctometry is used to test vision in dim light before and after sun blindness. The term vision is a bit misleading in this case because we do not directly measure visual acuity but rather the comprehensive cosurgery between visual acuity and contrast sensitivity in mesopic conditions. It is an examination method to detect retinal diseases such as hereditary retinal disease retinitis pigmentosa.
It is one of the most important examinations in refractive surgery which, besides diagnostics, can also help patients to demonstrate vision after sun glare in the early postoperative period.
It is one of the most important examinations in refractive surgery which, besides diagnostics, can also help patients to demonstrate vision after sun glare in the early postoperative period.
Degraded vision in the dark can be observed, for example, in people with myopia, cataract or with the mentioned diseases of the retina causing night-blindness, or temporarily after refractive surgery (laser surgery or lens replacement).
At our clinic, we conduct examinations using the Oculus Mesotest II device.
OCULUS Mesotest II
Apparatus for program-controlled examination of vision in the dark and sensitivity to glare.
Mesotest II is a device to check the vision in the dark and sensitivity to glare. Tests of vision in the dark and susceptibility to glare are important additions to the testing of photopic vision (vision in normal light conditions), in particular if it is necessary to assess the capability of night vision when driving at night and for occupational health assessments.And if the patient has intraocular lenses or has undergone refractive surgery, it is advisable to check their vision acuity in the dark and glare sensitivity before and after surgery and possibly prescribe tinted glasses.
Mesotest II is a standardized device approved by the German Ophthalmological Society for the testing of vision in the dark and sensitivity to glare
The examination is performed using Landolt rings with visualization degree 0.1. Displaying of a Landolt ring is possible in six positions. Four contrast levels are examined without glare (ambient lighting 0.032 cd/m²) and four contrast levels with glare (ambient lighting 0.10 cd/m²).
The device is designed so that the results of the measurement are independent from different pupillary distances of patients.
Measurements can be done even in bright rooms, because the device has a closed view.
