A 73-year-old woman presented for a third opinion regarding decreased vision. Specifically, for the past year she has noticed increasing blurry vision and glare from bright lights in her right eye. She no longer feels safe driving at night.
In addition, the patient said her glasses prescription has been changing, she does not like wearing glasses, and she is not interested in wearing contact lenses. Her past ocular history is significant for monovision LASIK (OD distance and OS near) 15 years ago because she did not like glasses or contact lenses, which she began wearing at age 45.
The patient desires improved vision OD. The first ophthalmologist she consulted was a refractive surgeon who diagnosed a cataract and recommended cataract surgery. She sought a second opinion from a prominent cataract surgeon who told her that she did not have a visually significant cataract but instead had misshapen corneas from the prior LASIK surgery (i.e., keratectasia).
He said she was not a surgical candidate and recommended a rigid gas permeable contact lens to improve her vision. The patient was confused by this lack of agreement regarding her diagnosis and therefore came to see me for a third opinion.
On examination, her BSCVA was 20/25-2 OD and 20/20-1 with a manifest refraction of +2.00+0.75x145 OD and +0.50+0.25x45 OS. Glare testing resulted in deterioration of visual acuity to 20/40 OD and 20/25-1 OS. Slit lamp examination revealed clear corneas with well-centered LASIK flaps OU, and 1+ nuclear sclerotic cataracts with 1+ cortical spokes OD greater than OS. The rest of the anterior and posterior segment exam was normal OU. Corneal pachymetry was normal, and topography was obtained:
What is the cause of this patient’s decreased vision and how would you counsel her? I explained to the patient that she does indeed have a visually significant cataract OD that is causing her symptoms and I agree with the first doctor who recommended cataract surgery. Furthermore, I explained that her LASIK procedure was a hyperopic treatment, which regresses over time and produces central corneal steepening consistent with her current corneal topography. I reassured her that she does not have keratectasia. I also told her that a contact lens would be of no benefit. I subsequently demonstrated this to her by performing a RGP contact lens over-refraction which did not improve her vision.
Discussion: This case illustrates the importance of a careful history and the role of corneal topography and its correct interpretation. Although most laser vision correction procedures are myopic ablations, it is important to know exactly what type of treatment was performed. If the patient is not aware and records are not available, then inquiring about previous glasses wear and reading vision can uncover the patient’s original refractive state. Myopia generally begins in the first two decades of life and presbyopic myopes can read without correction, whereas low hyperopes and emmetropes typically first need glasses in their early 40s for reading and then may require distance correction too as they lose the ability to accommodate. Corneal topography shows a characteristic pattern of central flattening for myopic ablations or central steepening for hyperopic ablations.
This patient’s topography maps are consistent with a hyperopic treatment, but there are other clues to the type of procedure this patient had: her history of glasses wear began when she developed presbyopia, and the correction regressed in both eyes (typical for hyperopic treatments).
Regarding the presumed diagnosis of keratectasia by the second ophthalmologist, the absence of corneal thinning in the area of steepening, the normal to slightly steep keratometry values, the lack of significant astigmatism, and the long interval between her LASIK procedure and her symptoms make keratectasia unlikely. Although keratectasia has been reported after hyperopic LASIK, it is extremely rare. More commonly this iatrogenic complication is seen within several years following myopic ablations. However, late onset keratectasia (up to 11 years) has been reported after myopic LASIK and pregnancy has been reported to be a factor (up to 9 years after myopic treatments).