Optometry school faculty work with inquisitive students every day. We reached out to recent graduates and asked whether they had any contact lens-related questions that were not covered in their contact lens classes. This column will address some of their responses.

How Do I Decide on a Material for a GP Lens?

Many practitioners are aware of the variety of materials available but are unsure of when to ask their lab for specific ones. If a patient will be wearing lenses overnight, has a history of corneal edema, or needs a high-plus prescription, a high-oxygen-transmissible material is indicated. Likewise, high-minus prescriptions may also require some consideration as to the material selected. The base curve of these lenses can flatten over time from rubbing. Therefore, a more durable material might be a good choice. Lastly, if a patient’s lenses tend to accumulate deposits, a coating will help with wettability to reduce that issue, so select a material that allows for applying that coating.

What In-Office Modifications Can Be Made to GP Lenses?

Practitioners who have years of GP experience often perform in-office power changes, edge modifications, peripheral curve changes, and polishing. For edges that are chipped or rough, it’s convenient to roll and polish those edges in-office. Modifications beyond this, however, are generally not recommended with modern materials. While peripheral curve and power modifications can be performed on some materials, this makes it impossible to exactly duplicate the result in a replacement lens. Manufacturers caution that any modifications, even polishing, can affect wettability, and any lenses that have a coating or a surface treatment should absolutely not be touched. If protein deposits need to be removed from most non-coated GP lenses, it is recommended that practitioners use a biweekly deep cleaner as opposed to polishing. Overall, modern materials are very different from PMMA, and it is best to leave modifications to the lab and to replace an older lens rather than attempt in-office modifications.

When Is a Lens Too Tight?

When looking at a soft lens, one of the key attributes that practitioners assess is lens movement. Ideally, lenses should move with every blink; when they do not, many practitioners conclude that the lens is tight. However, most current lenses do not move much. Often, selecting a flatter base curve when a lens seems “tight” results in a lens that does not center well and may move even less with the blink. The best way to determine whether a lens has an acceptable fit is to check for lens movement with a lid push method. As long as the lens moves and recovers well with a push-up test, it is not too tight. Movement with blink and lag on upgaze may provide less valuable information.

Final Thoughts

If one of the authors (Dr. Pence) might be allowed a small indulgence, I would like to thank the current and all past editors and staff of Contact Lens Spectrum who have been so terrific to work with over the past 11 years. It has been an honor and a privilege to contribute to this column, and the feedback and encouragement from readers over the years has been greatly appreciated. While this is my last contribution for this column, I hope that the dialog, relationships, and friendships that it helped promote will continue far into the future. CLS

Special thanks to Mike Johnson, George Mera, and Steve Webb for serving as resources for this column.