AVT Scleral Supporting Info

14828 West 6th Ave., Ste. 15B

Golden, CO 80401

Ph: 303-384-1111

Ph: 888-393-5374

Fx: 303-384-1124

Advanced Vision Technologies


Supporting InformationA Simplified Approach To Scleral Lens Fitting


Golden, CO 80401

Ph: 303-384-1111

Ph: 888-393-5374

Fx: 303-384-1124



Background

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A Simplified Approach For Scleral Lens Fitting

BLANCHING

Scleral lens fitting has been utilized primarily for the fitting of highly irregular corneas due to trauma, post surgical or genetic considerations. Until recently, very little was known about the sclera and these very large designs which placed the entire weight of the lens beyond the cornea and limbus.

During the past 20 plus years, Scleral lenses have been fit by very few Practitioners with designs re-maining unchanged throughout the years. The basic designs were based on many assumptions having now been proven obsolete. Previous scleral designs incorporated parameters consisting of a central base curve and peripheral system designed to create enough sagital vault to completely clear the cornea while aligning the peripheral carrier of the lens with the sclera.

Traditional thinking of the basic sclera considered the sclera to be a very flat convex curvature. Traditional scleral designs incorporated conventional corneal lens peripheral systems consisting of a series of flattening peripheral curves to create consisting of a series of flattening peripheral curves to create both alignment and edge clearance on the sclera.

This traditional approach featuring optic zones routinely smaller than 8.0 mm created a necessity of excessively high sagital values to allow the lens to adequately clear the entire cornea and limbal area.

This high sag fitting philosophy complicated the fitting process with trapped bubbles underneath the This high sag fitting philosophy complicated the fitting process with trapped bubbles underneath the lens due to the high clearance of the central curve and adhesion or seal off at the lens edge or the junctions of the mid peripheral system. This seal off, creates blanching, a white appearance of the sclera inside the lens diameter caused from the decrease of blood flow to the cornea. Upon removal of the lens, a compression ring may be present where the blanching occured.

TRADITIONAL THINKING


Golden, CO 80401

Ph: 303-384-1111

Ph: 888-393-5374

Fx: 303-384-1124



Pacific University recently completed a large comprehensive study of the sclera. The study con-sisted of analyzing 48 patients, 96 eyes measuring 1536 angles. The method of measurement was having a decentered fixation point with the Visante OCT scan. Measurements were taken in four quadrants; superior, inferior, nasal & temporal averaging the angles of the Sclera at 10.0mm to15mm, & 15mm to 20mm.

A NEW understanding of the sclera has been discovered in that beyond limbus, the sclera is better defined as a tangent angle rather than a progressively flattening radius.

The Pacific Study shows the angle of the sclera at approximately 15mm to 17mm is quite consistent. The Pacific Study shows the angle of the sclera at approximately 15mm to 17mm is quite consistent. The further out on the sclera the more toricity is found due to the muscles attaching to the orbital globe. No correlation between the steepness or flatness of the cornea is found in relationship to the sclera shape. However there is a slight apparent relationship of toricity meaning when a cornea exhibits a great amount of toricity the sclera often manifests toricity. Toric applications in the Carrier Angle can be designed and manufactured as needed.

Understanding the Sclera is defined as a tangent angle rather than radii. Knowing the average Understanding the Sclera is defined as a tangent angle rather than radii. Knowing the average sclera angle is quite consistent with most eyes, a standardized Tangent Carrier System in conjunc-tion with an increased central Optical Zone more easily effectively vaults the cornea and limbus while providing alignment with the soft conjunctiva of the sclera.

For Consultation – Call 888-393-5374 or 303-384-1111


Golden, CO 80401

Ph: 303-384-1111

Ph: 888-393-5374

Fx: 303-384-1124



Featuring Limbal Clearance Technology

AVT Scleral Diagnostic System Terminology:

Carrier Angle is defined as Standard, Flat or Steep Carrier Angles *Carrier angles can also be ordered 1 Step or 2 Step Flat or Steep etc.

The System is designed to provide clearance in three critical areas of successful scleral lens fitting, the Apical Clearance (AC), Limbal Clearance (LC) and Peripheral Clearance (PC).

RC(Reverse Curve) is a steep transitional zone between the Central Base Curve and Carrier Angle providing increased vault centrally as well as more clearance over the limbus.

AVT Scleral Tangent Carrier Design

BASE CURVES

CLEARANCES

CARRIER ANGLESAngles


Golden, CO 80401

Ph: 303-384-1111

Ph: 888-393-5374

Fx: 303-384-1124



18 Lens AVT RC Scleral Set

The most critical areas of a proper scleral fitting relationship:

Tangency of the lens carrier to the scleral angle. The desired well fit relationship of the AVT Scleral

lens is to assure complete Apical Clearance (AC) of the cornea allowing no impingement of the lens

surface across the cornea while providing Limbal Clearance (LC). The entire weight of the lens

should be resting on the sclera with no impingement at the peripheral edge. If the Peripheral Clear-

ance (PC) is not enough, a restriction of blood flow to the cornea (blanching) will occur.

REDUCES COMPLICATIONSIMPROVES FITTING RELATION

Simplified Approach Fitting Scleral Lenses

BLANCHINGNON BLANCHING

AVT Scleral Supporting Info

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