Multifocal vs Monovision - thru-luminance (scotopic-mesopic-photopic) comparison of two presbyopia correction ways

Purposes: a) comparison of two presbyopia correction methods – with multifocal and monovision contact lenses – by means of precise contrast sensitivity measuring under scotopic, mesopic and photopic conditions simultaneously; b) new computerized AltTechNV Thru‐luminance CSF test trial operation. Methods: contrast sensitivity of 14 initial presbyopes (40÷51 y.o., never wore contact lenses, used glasses for reading ≤+2,0D), and of 3 control presbyopes with anisometropia (∆D: 1.0; 1.25; 2.0) of the same age group (43; 46; 47 y.o.) was measured binocularly in multifocal contact lenses and monovision ones of equal power, in arbitrary sequence. We used computerized AltTechNV Thru‐luminance CSF test, ver.4.05. Measurements were made under luminance levels of 0.34; 3.4; 10.0; 20.0; 34.0 and 100.0 Lux (controlled with luxmeter “Meterman LM631”, on the eyes level, in the monitor direction). Refractive errors were controlled using auto refractometer NIDEK AR‐330A. The measurement for each type of lenses was prolonged up to 24÷30 minutes, and we should secure the eyestrain control. For pupil size monitoring, the camcorder with infrared target light was used (built‐in infrared filter was removed preliminary). Results: the most evident difference of contrast sensitivities (up to 37%) was observed at low and medium spatial frequencies (2; 3; 5; 8 cpd) under scotopic (0.34 Lux) and mesopic (3.4; 10.0; 20.0 Lux) luminance conditions, in favor of multifocal lenses, as compared with monovision. There were no significant difference at high frequencies (12; 20 cpd) under light mesopic (34.0 Lux) and photopic (100.0 Lux) conditions. All of three anisometropes of control group showed no significant CSF difference between multifocal and monovision lenses – under all luminance levels. Conclusions: visual quality of presbyopes who use multifocal and monovision lenses differs significantly. For presbyopes without anisometropia multifocal lenses provide significantly better visual quality under low luminance conditions, as compared with monovision lenses. The special attention should be paid to the difference of contrast sensitivities at low frequencies, because this parameter indicates the reduced ability to detect the large moving objects. Ignoring this point may entail the increased danger, e.g. for night driving. Interestingly, this difference could not be revealed with traditional vision testing tools. Contrast sensitivity at high spatial frequencies represents the visual acuity, and equality of CSF meanings at high frequencies explains why there were no significant divergence between the lenses of different design was found using both visual acuity tests (even low‐contrast ones) and CSF photopic /mesopic tests, so far.