The Impact of Light Conditions on the Efficacy of Multifocal Intraocular Lens Implantation in Activities of Daily Living

Primary objective of this study is to identify the optimal task lighting conditions (in terms of light intensity and light temperature) for 10 activities of daily living (ADLs) that require near or intermediate vision acuity in a validated ADL simulation framework for a sample of patients who underwent presbyopic correction with bilateral multifocal intraocular lenses (IOLs) implantation, and to compare their capacity to perform ADLs (ADL scores) between three study groups (SG): SG1. patients implanted bilaterally with trifocal diffractive IOLs, SG2. patients implanted bilaterally with bifocal hybrid (diffractive-refractive) IOLs, SG3. patients implanted bilaterally with monofocal IOLs

Patients who underwent presbyopic correction with bilateral implantation of multifocal IOLs are supposed to have sufficient uncorrected vision capacity for ADLs that require near (ie. book reading) or intermediate (ie. reading in a computer screen) vision acuity. However, it is known that light intensity and light temperature has a great impact on near/intermediate vision capacity, but also patients that have been implanted with multifocal IOLs are most likely to present completely different lighting needs than patients with their own crystalline lenses.

Primary objective of this study is to identify the optimal task lighting conditions (in terms of light intensity and light temperature) for 10 ADLs that require near or intermediate vision acuity in a validated ADL simulation framework for a sample of patients who underwent presbyopic correction with bilateral multifocal IOLs implantation, and to compare their capacity to perform the ADLs (ADL scores) in 9 different lighting combinations (combinations of light intensity and light temperature) between three study groups: SG1. patients implanted bilaterally with trifocal diffractive IOLs, SG2. patients implanted bilaterally with bifocal hybrid (diffractive-refractive) IOLs, SG3. patients implanted bilaterally with monofocal IOLs

The study is conducted in an experimental facility in a hospital room with a dimension of 6.87 × 2.9 × 3 m (depth × width × height) and flat white surface walls (reflectance: 70%). Αn advanced light diffusion system has been installed, which consists of four linear LED luminaires producing low glare (unified glare rating (UGR) \< 19). Light intensity (dimming / in foot candles - fc) and light temperature (white tuning / (in Kelvins - K) have been adjusted using the Casambi wireless control application (Casambi Technologies Oy Inc., Espoo, Finland), which uses integrated Bluetooth mesh technology and secures maximal uniformity at different user-defined lighting settings. The four LED luminaires have been mounted on the ceiling. The exact luminaire positioning and the amount of the provided luminous flux have been defined using the RELUX light simulation tool (version 2021.1.1.0) (Relux Informatik AG, Münchenstein, Switzerland) prior to the installation. The confirmation of illuminance and on-site adjustments have been confirmed with the Extech Lux Meter EA30 (Extech Instruments Corporation, Nashua, NH, United States). As regards photometric properties derived from lighting laboratory photometric measurements, the correlated color temperature (CCT) of the luminaires ranges between 2700 K and 6500 K, emitting a maximum luminous flux of 10,626 lm and 11,508 lm, respectively. The exact radiant flux P(λ) emitted from the selected light sources has been measured using a Konica Minolta CL-500A spectrum meter for the wavelength range of 380-780 nm using a step of 1 nm. The power of each luminaire is 106 W, resulting in luminous efficacy of 100.2 lm/W and 108.6 lm/W for 2700 K and 6500 K, respectively. The color rendering index (CRI) is 84. The wireless dimming control system enables dimming from 0% to 100% and vice versa.

The 9 lighting combinations (light intensity, light temperature) are the following:

3000 K - 25 fc, 3000 K - 50 fc, 3000 K - 75 fc / 4000 K - 25 fc, 4000 K - 50 fc, 4000 K - 75 fc / 6000 K - 25 fc, 6000 K - 50 fc, 6000 K - 75 fc

In specific, patients address the following ten ADLs:

1. Phone Book Search (PBS), 2. Supermarket receipt (SupRe), 3. Book reading (BR), 4. Cellular message (CM), 5. Cellular entry search (CES), 6. Reading computer screen (RCS), 7. Drops bottle reading (DR), 8. Subtitles reading (SubRe), 9. Open door test (ODT), and, 10. Screwdriver test (ST).

Test-retest reliability will be assessed by calculating intraclass correlation coefficients (ICCs) for all ADLs at the nine combinations of light conditions in two different visits with an average 15-day time window to prevent memory effect.

Eligibility Criteria:
Inclusion Criteria:

* Age older than 18 years old
* Diagnosis of senile cataract either stage 2 or 3 of the Lens Opacities Classification System III (LOCS-3) grading scale - Patients underwent phacoemulsification and bilateral implantation of IOLs \[trifocal diffractive, bifocal hybrid (diffractive - refractive) or monofocal\]
* Fluency in written and verbal Greek language
* No severe cognitive impairment

Exclusion Criteria:

* Αstigmatism \>1.00 diopters
* Glaucoma
* Intraocular pressure-lowering medications
* Corneal pathology
* Fundus pathology
* Diabetes mellitus
* Autoimmune diseases
* Former incisional eye surgery
* Posterior capsule rupture or lens misalignment
* Neurological, psychiatric or mental diseases that interfere with visual acuity and reading process
* Inability to understand the objectives of the study