الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The term presbyLASIK indicates a corneal surgical procedure based on traditional LASIK to create a multifocal surface able to correct any visual defect for distance while simultaneously reducing the near spectacle dependency in presbyopic patients. Presbylasik was suggested to correct presbyopia with acceptable results for both central and peripheral techniques.
Previous theoretical studies using ray tracing showed that presbyopia correction by central steep island or global optimum are the two promising approaches for presbyopia correction at the cornea. In addition, as the pupil decreases in diameter with accommodation, the central model appears to be the most advisable model to achieve optimal multifocality. However up to this moment, all clinical evidence was based on subjective data coming from patient examination. Physical methods as ray tracing can analyse optical surfaces and give informations about optical performance of these surfaces.
In this prospective investigation, we tried to demonstrate whether the induction of central increases in corneal curvature can decrease the spectacle dependence for near vision in the hyperopic and myopic presbyopic patients. In addition to analyse objectively the outcome of central presbylasik as obtained ray tracing analysis and to determine its correlation with clinical data.
This study was conducted in Vissum instituo oftlamologico de Alicante, Spain in the period from January 2011 to September 2011. The study included 30 eyes (18 Myopic presbyopes and 12 Hyperopes presbyopes) with the mean age in myopic group of 47.33 4.2 years ranging from (42 – 56 years) and in hyperopic group of 52.6 4.6 years ranging from (46 – 58 years). The follow up period was 3 months.
Inclusion criteria were patients older than 40 years old without specific upper limit on the age whenever all ocular conditions are met. sphere up to +5.00 D, cylinder up to 3.00D in hypermetropic presbyopes, while in myopic presbyopes, sphere up to -5.00 D, cylinder up to 3.00D is included. In all patients, the following criteria were met: corneal curvature (SimK) between 40 and 48D and central corneal thickness 500 m.
Exclusion criteria:
1. Ocular conditions: the following cases were excluded: patients with signs of keratoconus or abnormal corneal topography, severe local or allergic conditions (e.g. blepharitis, previous herpes simplex or zoster keratitis), severe dry eye, cataract and glaucoma. Monocular patients, patients with signs of amplyopia and patients with strabismus or nystagmus and thoses with inappropriate motivation or unreasonable expectations (e.g. in postoperative image quality and visual acuity) were also excluded. Patients with preoperative CDVA worse than 0.1 logMAR (20/25), Patients with preoperative CNVA worse than 0.2 logRAD (J4; 20/32) with +1.5 D addition were not included. Patients with ectopic pupils (more than 0.7 mm off-cantered) and patients with pupil diameter larger than 3.0 mm in photopic condition.
2. General conditions: pregnant and nursing women, patients with collagen vascular, autoimmune or immunodeficiency diseases and diabetes Mellitus were excluded.
Preoperative clinical procedures:
Patient demographics including age, gender, profession, hobbies, expectations, and family history. Detailed eye examination included the measurement of monocular and binocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected near visual acuity (UNVA), corrected near visual acuity (CNVA), and distance corrected near visual acuity (DCNV). The chart used for distance vision was ETDRS conform. The reading chart was: RADNER reading charts at 40 cm under illumination. RADNER reading charts is reported to be a valid and accurate way to assess reading performance and has been used to evaluate the reading performance with other IOL models. Near addition determined at 40 cm. Refraction including objective, subjective, and cycloplegic refraction. Slit-lamp examination, IOP measurement using Goldmann applanation tonometer and fundus examination. Ocular dominance testing was done using the “hole test” and pointing. Corneal topography and corneal aberromertry was done using the Sirius topography system (CSO, Italy) (combined Placido based topography with Schimpflug camera). Pupil measurement using (Procyon Pupillometer P2000SA, Procyon Instruments Ltd, London, UK) for assessment of photopic, scotopic, low and high mesopic pupillometry. Data entry to presbyMAX software was done according to the suggested nomograms.
Conclusions
• There are scientific evidences in literature indicating that presbylasik improves near vision and achieve near spectacle independency.
• Regarding the clinical outcomes of this study:
- Hyperopic presbMAX ablation profile needs further studies to improve the ablation profile and identify factors responsible for loss of BSCVA.
- Myopic presbyMAX ablation profile seems to have acceptable results for correction of distant vision while preserving acceptable near vision. The induction of less amount of negative spherical aberration after myopic central presbylasik is associated with better safety in this group.
• Regarding optical analysis outcomes of this study:
Ray tracing analysis shows acceptable correlation with the clinical results and can be used as a scientific objective method for assessment of DoF and for the purpose of optimization of central prebylasik.