A Quick and Easy Reference Guide to Troubleshooting RGP Lenses


Here is a basic cheat sheet to troubleshooting that problematic RGP patient.

We’ve all had the RGP lens wearing patient, for whom we order lenses for based off of their refraction and keratometry readings. Sometimes, the lenses fit perfectly, and other times, to our disappointment, they do not. With many warranties only covering one re-make, we need to scrupulously examine the causes of a poorly fitting lens, and ensure that the next lens that arrives in the mail is a perfect fit.

The most common elements that must be examined before beginning a troubleshooting process include:

  • Is the base curve too flat?
  • Is the base curve too steep?
  • Is there too much edge lift?
  • Are the edges too tight?
  • Is this a lid fit? Or an intrapalpebral fit?

The first critical step is to look at the fluorescein pattern!

Does the fluorescein pattern look like A or B?




A. Flat Lens                                                                    

  • Touch or bearing in the middle surrounded by clearance.
  • Darkness indicates pressure on the cornea.
  • Smaller darker areas mean even greater degrees of flatness (the smaller the area, the flatter the fit).
  • Large amounts of movement and de-centration.
  • Blinking causes a lot of movement, and the lens is dropped inferiorly if too flat.
  • For lenses that do not lid attach, the lens is pulled up on a blink, and then dropped back into position.

B. Steep Lens

  • Central area of clearance.
  • Much more comfortable because they fit tighter to the cornea.
  • Lack of lens movement.
  • Good initial comfort, but complaints of blurry vision or redness and irritation by the end of the day.
  • Centers well.

Steps to Correcting for Lens Types:

A. Flat Lens:

  1. Increase the diameter first by 0.4mm.
  2. Steepen the base curve by 0.1mm.
  3. Don’t forget to change the power! Flatten – add plus.

B. Steep Lens:

  1. Decrease the diameter first by 0.4mm.
  2. Flatten the base curve by 0.1mm.
  3. Don’t forget to change the power!  Steepen – add minus.


(For every half step change in BC, change power by a quarter)


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About Courtney Dryer

Courtney Dryer
Courtney Dryer is a 2011 graduate of SCO. She opened 4 Eyes Optometry in her hometown of Charlotte, NC in February of 2013. After 5 years, the practice name was changed to Autarchic Spec Shop to renew the practice's commitment to independent optometry. In addition to consulting with new graduate optometrists on start-up practices, she contributes regularly to New Grad Optometry and has guest blogged for Invision Magazine. The unique design of her boutique practice was featured in Women in Optometry. In 2015, Vision Monday named her a Rising Star, and one of the most influential women in optical.


  1. Antonio Chirumbolo

    Great work. I really enjoy attempting to fit my own patients using these tips rather than leaving it all up to the lab!

  2. Matthew Geller

    Lol, this was so helpful. I have an RGP patient about to come in complaining of discomfort and I have a feeling the lens is too flat. This was a great article. Do you do any ortho-k? I would love to get a guide on that!

  3. For the spherical examples: wouldn’t you want to flatten BC after increased the diameter? Increased OAD would increase sag so you would flatten BC to maintain fit. Maybe I am misreading?

    • Courtney Dryer

      Hi Kari,

      Thanks for your question. The steps listed in #1 and #2 are both listed as options that you may do for changing the same problem, and not necessarily steps to change in order. If you increase the diameter, you do need to flatten the base curve, you are correct. I hope that helps. Sorry for the confusion.

  4. Anna Slemp

    I have a patient who wanted to switch from distance GPs to monovision. She’s complaining of the near lens fogging after being in for about 15 minutes. Do I need to adjust the base curve when I changed the power? The lens appeared to be fitting well on exam, just wasn’t wetting well.

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