Lens Design
Maxim is a semi-sclera lens. The standard trial lenses are 16.0mm in diameter. The Maxim design performs very well on irregular corneas including keratoconus, corneal trauma, pellucid marginal degeneration, penetrating keratoplasties, post LASIK and RK patients. It incorporates a proprietary multiple posterior curve system to obtain corneal alignment. Patients who wear Maxim will have exceptional comfort and clarity throughout the day.

Pre-Fitting Examination
Assuming there are no contraindications, begin by taking the Keratometer readings. Determine the flatter K reading ("Flat K") and amount of corneal astigmatism. If corneal topography is done take note to the steepest area on the map and the temporal quadrant. In addition you want to observe the limbal size of the cornea.

Selection Lens Size
Maxim trial lenses are available in 16.0mm diameter. Occasionally one may need to fit a smaller 15.4 or a larger 16.4mm lens. This will be dependant on the patient's corneal size. Since most patient's corneas are 11.5mm in diameter a 16.0 mm lens will be selected. The overall diameter should extend at least 2mm beyond the limbal area of the eye. This is very important since Maxim needs to bear primarily on the sclera and not the cornea.

Proper Lens Diameter

Choosing Base Curve
The most difficult parameter to determine on a distorted corneal is the base curve. An accurate "K" reading is many times difficult to obtain. Below is a suggested initial base curve guide. For "Sunken post surgical", such as RK failure, two trial lenses are available. For excessive flat central corneas, choose a flatter central base curve. Ie: 8.88.bc.

A properly fit lens will have alignment over the cornea or only light corneal touch. The ideal vault will have 100 microns clearance over the steepest part of the cornea. Your goal is to find the minimum SAG Value that vaults the cornea with little or preferably no apical bearing.

Calculating Lens Power
Lens power is best determined by over-refraction with a trial lens in place. The spherical value of the over-refraction is simply added to the trial lens power to determine the power prescribed.

Center Thickness
Center thickness is a function of lens design and should be calculated by the laboratory.

Fluorescein Pattern
Lens selection should be aided by an examination of the fluorescein pattern. It helps to place the fluorescein in cup of the lens at insertion. The most accurate way to determine the proper SAG is to evaluate a trial lens that has apical touch. If there is central bearing the SAG value should be increase by 0.1mm for every 1.0mm of touch. You goal is to determine the minimum SAG that vaults the cornea with very little or preferably no touch. The ideal pattern will align cornea with out any bubbles at the limbus or under the optical cap and it will vault the steepest part of the cornea by only 100 microns or less. Once that is obtained, a close evaluation of the periphery is needed. There should not be any excessive edge lift or worse impingement in the conjunctiva. If there is excessive lift or impingement in the periphery, the lens edge should be adjusted. Contact your AccuLens consultant for assistance. Since a flat fitting lens is easiest to evaluate, we recommend that the first trial lens have some bearing on the apex. This way you can determine very accurately how much to increase the sag value for optimum vaulting.

Too Flat / Heavy Central Bearing with Limbal Bubble Increase Sag Value by 0.3 - 0.4mm

Bubbles
Sometimes at insertion a false bubble can be induced. It is very important when inserting the lens, that it be filled fully with saline and placed on the eye with the head down parallel to a table top. You do not want any bubbles because they can cause the cornea to become dry in those areas. A single fenestration is recommended and its purpose is for lens release and tear exchange. When dealing with corneas that have excessive corneal cylinder sometimes bubbles can form from the fenestration. If this occurs, reorder a lens without the fenestration. In addition, when fitting an excessively flat cornea, such as a post RK patient, central bubbles with the diagnostic lenses may not be able to be resolved. In this case, call your AccuLens consultant for a flat reverse design.

Edge
A proper edge should not lift off of the sclera or more importantly impinge into it. An edge that lifts excessive will cause lens awareness while an edge that impinges can cause edema, redness and discomfort. If the edge is not aligned with the sclera recheck to make sure that you have a minimum SAG that vaults the cornea. If you do have the appropriate SAG with an incorrect edge call our consultation department for advice on peripheral curve changes.

Ideal Fit
The lens should align with the cornea or exhibit only minimal bearing. There should not be any bubbles under the optical cap (too steep of a sag) or over the limbus (too flat of a sag). A Maxim lens will have very minimal to no movement. In addition, attention should be observed at the periphery. There should not be any conjunctival impingement or excessive edge lift with Maxim.

Insertion & Removal
Make sure your patient understands the importance of proper insertion and removal. When inserting a Maxim it is important that the concave surface be fully filled with saline so as to reduce the risk of induced unwanted bubbles. Most patients find that holding the lens between the index and middle finger works best. Since Maxim tends to settle on the eye, it needs to be pre-loosened before removal. We recommend irrigating with saline and massage the lens prior to blinking the lens out or removing with a dmv suction cup.

Troubleshooting
While not common, corneal edema may occur in some patients. A lens that vaults the cornea too much can cause this. Make sure to re-evaluate your SAG value. It should be the minimum SAG that vaults with very little or preferably no apical bearing (100microns). Another cause may be that the periphery of the lens is impinging into the conjunctiva. If this occurs flattening the PC's while maintaining the appropriate SAG is indicated. Lens awareness can occur if there is too much edge lift. Excessive edge lift is caused by either the PC's being too flat or the lens SAG being too low. If excessive edge lift is observed you should first determine if the SAG is appropriate. Often when the SAG is increased, the edge will improve. If the lens SAG is correct then a steeping of the periphery is indicated. The two most common causes for SPK are either from preservatives in the solution or excessive bearing on the apex. Because these lenses have very little or no movement, tear exchange is very slow to occur. Therefore, it is very important that a benign saline be used when inserting. This will eliminate any possibility of chemical irritation. On rare occasions metabolic debris accumulation can be an issue. Usually the patient will complain of decrease acuity after eight to ten hours wear. If this occurs have the patient remove, clean and re-insert during mid-day. Excessive redness can be a sign that the lens is fitting too tightly. Patients may complain that their wearing time is limited to only a few hours a day. Recheck the SAG value to make sure it is at minimum apical vault and adjust as necessary. If the SAG is appropriate then re-design with a flatter periphery.

Fitting Pearls
Lens Diameter should be at least 2mm larger than limbal area of the eye.
Your 1st trial lens should be flat fitting. That way, you can very accurately adjust the SAG up.
Central bearing, edge lift and or limbal bubbles indicate a flat fit.
Increase Sag value if there is a central bearing (0.1mm for every 1.0mm of bearing)
Deep pooling or central bubbles indicate a steep fit.
Decrease Sag value if you have a steep fit.
Ideal fluorescein pattern will be aligned or at most have very light bearing.
Edge should not impinge or lift excessively off of the sclera.
Your goal is to find the minimum SAG Value that vaults the cornea with little or preferably no apical bearing.