Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that Lila has been diagnosed with a second corneal sequestrum. Once a cat has one it is not uncommon to develop another because the conditions are right for them to form and your cat has the predisposition.
Corneal sequestrums can be seen in any breed of cat but is seen most frequently in Persians and other flat faced, big eyed breed cats.
Corneal sequestrums are areas of dead tissue in the cornea (clear outer part of the eye). They are often black or brown in color, may be superficial, only affecting the top layers of the cornea, or very deep and can lead to ulcers, pain and even the eye rupturing.
They form secondary to irritation, often from poor tear production, decreased blink reflex, and prominent eyes or secondary to a Herpes virus infection.
The fastest, most effective treatment is surgical removal of the dead tissue. This surgery is best done by a veterinary ophthalmologist as it is a delicate procedure and requires specialized equipment to properly visualize the defect. If the sequestrum is superficial then only the top few layers of the cornea need be removed and healing should take place with supportive care including antibacterial eye drops and artificial tears. If the sequestrum is very deep then a tissue graft from corneal or conjunctival tissue near the sequestrum, a donor cornea, or a collagen disc may be used to cover the defect while it heals.
Medical therapy is an option but it may take months or even years to be effective. It is best for superficial lesions. It includes artificial tears 4 to 6 times daily and antibiotic eye drops 2 to 4 times a day to prevent secondary bacterial infections, which can lead to deep, melting ulcers and the eye rupturing.
If we believe that the sequestrum formed secondary to a Herpes infection then anti-viral drugs like famcyclovir (Famvir, Novartis) can help. The recommended dose of famcyclovir is 62.5mg/cat once daily for seven days and increasing to 62.5mg/cat twice daily until the sequestrum resolves.
So the short answer is no, surgery isn't an absolute must but your girl will have a better outcome with it.
You may consider using artificial tear drops consistently long term as a preventative measure.
Please let me know if you have any further questions.