When Cornea thins ,weakens and endangers the vision !

 Keratoconus is a progressive, noninflammatory, bilateral (but usually asymmetric) ectatic corneal disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion. Visual loss occurs primarily from irregular astigmatism and myopia, and secondarily from corneal scarring. See the image below.

Fig 1 An optic section of Keratoconic cornea showing corneal thinning 

Patients with keratoconus may report the following:

• Distortions
• Glare/flare
• Monocular diplopia or ghost images
• Multiple unsatisfactory attempts to obtain optimum spectacle correction

Keratoconus is divided into mild, moderate, and advanced

Rigid contact lenses (CLs) are the mainstay of keratoconus (KC) treatment.

Patients with early keratoconus may successfully use spectacles or spherical/toric soft contact lenses. They may even rarely find that spectacle vision is superior to rigid contact lenses.

Patients with modest-to-advanced keratoconus almost always require rigid contact lenses.

 When rigid contact lenses are no longer tolerated, some patients can maintain contact lens wear and usable visions with hydrogel contact lenses, piggyback contact lenses, or scleral (haptic) contact lenses but usually at a physiological or visual cost.

Surgically removing central nodular scars by shaving the corneal surface (superficial keratectomy with a blade or excimer laser phototherapeutic keratectomy) may improve contact lens tolerance, decrease the rate of associated corneal abrasions, and preclude the need for corneal transplant.

Intrastromal corneal rings (Intacs) have been implanted for patients who have become intolerant to contact lenses, but these have been found to be more successful in modest than advanced disease.

Lamellar keratoplasty, or various types, especially deep anterior lamellar keratoplasty (DLAK) with "big bubble" technique, is being reconsidered as a surgical treatment for keratoconus.

More traditionally, these patients, including those whose vision is not correctable to better than 20/40, are referred for corneal transplants penetrating keratoplasty (PKP).

Clinical scenario : 

     A 32 years old  female known case of  Keratoconus was admitted  for bilateral implantation of posterior chamber, phakic toric ICL (STAAR Surgical, Nidau, Switzerland) for correction of high astigmatism in both of her eyes. 

Preoperative assessment 

       Her  visual acuity  was 20/25 in both eyes with 

      Pure astigmatic refractive error of – 5.00X180 degrees in right eye and 

         -4.75X180 degrees in left eye.

• Slit-lamp examination showed unremarkable anterior and posterior segment examinations with equally reactive pupils in both photopic (Figure 2) 
•  Applanation tonometric IOP measurements were 17 mmHg in right eye and 18 mmHg in left eye. 

Surgical steps :

• After performing superior and inferior paracentesis incisions, AC was filled with sodium hyaluronate 1.0%. A temporal 2.8 mm clear corneal incision was then made to inject ICL and each foot plate in turn was placed under the iris without causing any pressure on the crystalline lens.
• All viscoelastic material was carefully aspirated using irrigation aspiration (IA) tip and standered intracameral injection of 0.1 ml cefuroxime were administered. 
• Same steps were repeated with left eye and patient was sent to ward without complications.

Post operative course :

•  One hour after surgery, patient was experiencing headache and pain in both eyes,
•  IOP were 26 mmHg and 28 mmHg in right and left eyes respectively. 
• Two tablets of Acetazolamide 250 mg were given . IOP three hours after procedure dropped to 15 mmHg in both eyes and headeache decreased. 
• Moxifloxacin 0.5% q8h and prednisolone acetate 1% q6h eye drops were prescribed and patient was sent home in good condition.

Fig 2 First post operative day 

• In her first POD, uncorrected visual acuity UCVA was 20/30 in both eyes, IOP 13 mmHg in both eyes too , slit-lamp examination revealed formed AC with self sealed wound and normal depth bilaterally. Cells +3 in right eye and +2 in left eye were seen in AC without fibrin or posterior psynecia.
• We noticed that pupil in right eye was mid-dilated compared to left eye's pupil (Figure 2) with anisocoria more than 2 mm in diameter, but both pupils were rounded, regular and reactive to light 

• ICL was in place with normal vault in both eyes. No posterior segment reactions were noticed in right or in left eye. We advised the patient to continue same medication and to follow up after one week.
• Patient came one week after surgery  complaining of glare and photophopia in her right eye especially in daylight that she had to wear sunglasses all the time to alleviate her condition. 
•  IOP was 12 mmHg in both eyes. Slit-lamp examination was normal 
•  Anisocoria still the same with light reflex in the right eye being sluggish than the left and focal patches of iris atrophy and de-pigmentation start to appear in the right pupil mainly inferonasally . Steroid eye drops were tapered in left eye and kept in right eye with administration of pilocarpine 2% eye drops BID and follow up after 1 week.
• Two months later, the patient was not complaining of any glare or photophopia ,and she was not taking any medications. UCVA became 20/20 in both eyes. IOP was 14 mmHg in right and 15 mmHg in left,  occasional AC cells in right eye, decreased degree of anisocoria with regular , rounded and reactive pupils, She was happy with the result of her surgery but she still wonders about the exact cause of her condition and possible complications in the future. We assured her and explained the possible cause and sequel of her condition and advised her to follow up after six months if there was no complaints.

FURTHER READING  : CLICK HERE  KERATOCONUS

This case was contributed by 

Dr Talal Al Tomali

Associate Professor 

of Ophalmology &

Dean clinical affairs 

College of Medicine Taif University KSA