Multi-formula Optimization of Second Eye Refinement According to Direction of the Prediction Error of the First Eye

Study Overview
=================
Brief Summary
-----------------
Prediction errors for the first (PE1) and second eyes (PE2) were obtained in the intra-ocular lens power calculation for 4 formulae (HofferQ, SRK II, SRK/T and Holladay 1). The optimal correction factor for each formula was determined as the one resulting in the lowest mean absolute error. A similar analysis was performed in the negative and positive PE1 subgroups.

Detailed Description
-----------------
Retrospective case series study. A retrospective chart review was conducted, which included demographics (age and gender) and several parameters for both the first and second eyes: surgery date, axial length, keratometric corneal power in 2 meridians, predicted intra-ocular lens (IOL) power recommended for plano target in each formulae (HofferQ, SRK II, SRK/T and Holladay 1), implanted IOL power, predicted post-operative refraction for the implanted IOL for the 4 formulae, observed post-operative refraction in spherical equivalent and post-operative best corrected visual acuity. The prediction error was calculated for the first eye (PE1) as the difference between the observed post-operative refraction in spherical equivalent and the predicted post-operative refraction by the IOL Master for the implanted IOL. This was obtained for the 4 formulae. The prediction error for the second eye (PE2) was obtained in a similar fashion. The optimal partial adjustment for second eye refinement was obtained subtracting a portion of the PE1 from the PE2 (PE2-xPE1, where 0≤x≤1) for the 4 formulae. The optimal correction factor was determined for all formulae by using an array of different proportions of PE1 that were applied to the second eye. The values ranged from 10% to 100%, with increments of 10% each.

Official Title
-----------------
Multi-formula Optimization of Second Eye Refinement According to Direction of the Prediction Error of the First Eye

Conditions
-----------------
Cataract

Intervention / Treatment
-----------------
* Procedure: Phacoemulsification cataract surgery


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients having performed bilateral cataract surgery between 1st October 2012 and 24th April 2014 in a single ophthalmological center (Centro Hospitalar Baixo Vouga, Portugal) Exclusion Criteria: Inadequate follow-up Incomplete medical records Previous or combined ocular surgery Manual extracapsular cataract extraction and not phacoemulsification Corneal sutures Implantation of any other IOL type different from Abbott Tecnis® 1-piece IOL (Abbott Laboratories Inc., Illinois, USA), ZCB00 IOL implanted in the sulcus Intra or postoperative complication Post-operative best corrected visual acuity worse than 5/10 Corneal astigmatism>3.00 D

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Main group<br>Patients having performed bilateral consecutive cataract surgery between 1st October 2012 and 24th April 2014 in a single ophthalmological center (Centro Hospitalar Baixo Vouga, Portugal). | Procedure: Phacoemulsification cataract surgery<br>* Phacoemulsification of cataract (opacified lens) using clear corneal approach. Implantation of a intra-ocular lens in the capsular bag<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Second eye mean absolute error (mean of the absolute value of the prediction error) |  | 6 weeks after date of cataract surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of second eyes with a post-operative refraction within ±0.50 D and ±1.00 D of the targeted refraction |  | 6 weeks after date of cataract surgery |