What is Lens-Induced Glaucoma?
Lens-induced glaucoma (LIG) is a type of glaucoma linked with degenerated old-age cataracts. It was first mentioned by Gifford in 1900, and was also separately described by Von Ruess. Von Ruess identified LIG as a condition where the lens substance gets naturally absorbed through its unbroken capsule.
Various similar conditions have been noted over many years in medical literature. LIG behaves like acute angle-closure glaucoma, another form of glaucoma. However, in LIG, the pressure inside the eye is normal, the angles in the other eye are open, and symptoms usually ease quickly after cataract removal.
Depending on how it develops, LIG can be split into two categories:
1. Related to the lens protein: Here, the lens protein leaks, either through an unbroken or broken lens capsule. This category includes Phacolytic glaucoma, Lens-particle-induced glaucoma, and Phacoanaphylactic glaucoma.
2. Blocked flow of the eye fluid: Here, the normal flow of fluid from the back to the front of the eye is blocked. This category includes Phacomorphic glaucoma and Pupillary block glaucoma.
There are some reasons, like pseudo-exfoliation glaucoma and ciliary block glaucoma, which are debated as types of LIG.
What Causes Lens-Induced Glaucoma?
Congenital Ectopia Lentis (EL), a condition where the lens of the eye is not in its normal position, can obstruct the flow of eye fluid. This can show up in various ways:
* In Marfan syndrome, the lens typically shifts to the upper outer part of the eye. Sometimes, it can abruptly dislocate, interestingly often happening during early childhood.
* In Homocystinuria, the lens typically shifts to the lower inner part of the eye. It can suddenly move into the front part of the eye, and an increase in eye pressure is common.
* In Weill-Marchesani syndrome, the eye has a small, round lens, underdeveloped parts responsible for fluid flow, increased eye pressure, and are connected with a type of glaucoma where the normal fluid drainage site of the eye is in an abnormal location.
* Other conditions that can lead to this include Ehler-Danlos syndrome, sulfite oxidase deficiency, hyperlysinemia, aniridia, Alport syndrome, Axenfeld-Rieger syndrome, and Peter anomaly type 3.
There are also situations when this condition can occur because of external factors:
* Trauma can cause the lens to move to the front part of the eye and can increase eye pressure. Injuries that cause the lens to rupture increase eye pressure immediately in the inner part of the front eye, or after some time in the outer part of the front eye.
* After surgery, remaining lens material can trigger a rapid rise in eye pressure in the inner part of the front eye or a slow rise in pressure in the outer part of the front eye over time.
* Intumescent cataract can cause a slow rise in pressure in the middle of the eye.
* Micro-ruptures in the lens capsule can cause an increase in pressure in the outer part of the front eye.
Risk Factors and Frequency for Lens-Induced Glaucoma
Ectopia lentis, a condition where the eye lens is displaced, shows different rates in developed and developing countries. In developed nations, where healthcare is more accessible, congenital ectopia lentis – the form you’re born with – is more common. It’s estimated that 6.4 in every 100,000 people have this condition.
Meanwhile, in developing countries where resources are limited, a version of ectopia lentis that comes from severe age-related cataracts is more common. When these cataracts are first diagnosed, up to 2.4% of people also have this lens displacement. Interestingly, this subtype affects more women than men.
Signs and Symptoms of Lens-Induced Glaucoma
Patients with Lens-Induced Glaucoma (LIG) often have several eye-related symptoms. These include:
- Redness in the eye that comes on suddenly
- Pain in one eye that also occurs suddenly and might come with a headache, nausea, and vomiting
- A slow, gradual loss of vision, which often happens in cases where the patient has cataracts
- Seeing halos of color, being overly sensitive to light, and excessive tearing
Doctors need to know a detailed history of these symptoms: when they started, how long they’ve lasted, and whether they have gotten worse over time. It’s important to note if the patient had similar symptoms in the past or any eye surgery. Doctors should also find out if the patient has any conditions that would make them unsuitable for treatment with systemic steroids, like bone loss, stomach ulcers, mental health issues, or tuberculosis.
Testing for Lens-Induced Glaucoma
Evaluating lens-induced glaucoma involves several steps:
* Checking the best-corrected eyesight and any improvement with the use of a pinhole. In some cases, the vision might be checked with the pupil enlarged.
* Observing the symmetry of the face and the position of the head.
* Checking the alignment of the eyes: If one eye sees poorer due to advanced cataracts, the eyes may not line up correctly. Cataracts in one eye since childhood suggest a poor outcome for vision in those cases.
During the clinical examination, the doctor will check for:
* Swelling and redness in the area surrounding the eye.
* Redness and swelling in the whites of the eyes.
* Veins in the white part of the eye that appear larger than normal.
* Changes in the cornea (the clear, dome-shaped surface of the front of the eye) due to increased eye pressure.
* Decreased space in the front of the eye, signs of inflammation, and presence of lens particles in the fluid of the eye.
* Bending forward of iris (colored part of the eye) and signs of inflammation lasting a long time. Also, the pupil might appear vertically oval in shape due to higher eye pressure. There might be a classical mid-dilated pupil in some cases. Some long-term cases might show a ruffled pupil. A quick response to light in the other eye suggests a good vision outcome.
* The lens might show a puffy mature cataract. There might be visible damage to the lens in some cases. The lens might be positioned more forward in some cases.
* Difficulty in viewing the backside of the eye due to complete cataracts.
Further tests involve:
* A specific test (Goldmann Applanation Tonometry) considered as the gold standard for measuring eye pressure.
* Eye examination to assess the angle where the iris meets the cornea.
* Using eye ultrasound to provide an image of the backside of the eye if it’s not visible.
* Anterior segment ocular coherence tomography (AS-OCT): It measures the space and length of the eye, which can help to understand the disease. Some rare cases might require testing the fluid humor to understand the disease better and differentiate it from possible infections.
Treatment Options for Lens-Induced Glaucoma
The main objective in treating certain eye conditions is to control the pressure inside the eye, also known as intraocular pressure (IOP). The key to this is removing the problematic lens matter.
Different ways of managing eye pressure include:
* Laser peripheral iridotomy (LPI): This procedure can help partial angle-closure glaucoma and pupillary block glaucoma. It can lessen some of the blockage but may not totally control eye pressure.
* Eye drop medication: The first go-to treatment includes medications like beta-blockers, alpha-agonists, and carbonic anhydrase inhibitors. Other medications like prostaglandin analogs and miotics can also be used, however, they could increase the eye inflammation.
* IOP-lowering agents: These are systemic drugs, such as hyperosmotic agents (like mannitol) and carbonic anhydrase inhibitors (acetazolamide), that enhance the effect of eye drops. Regularly monitoring kidney function and serum electrolytes is crucial when using these drugs.
* Steroids: These can be systemic or drop form and are used to reduce inflammation in certain types of glaucoma before definitive cataract surgery.
A certain procedure called pars plana vitrectomy may sometimes be required before cataract surgery. This is done when there is not enough space in the front part of the eye to safely perform the procedure, especially in cases of advanced or swollen cataracts.
The removal of the lens, ideally done after sufficiently controlling eye pressure, includes:
* Conventional large incision cataract surgery (ECCE), small incision cataract surgery (SICS), or phacoemulsification are used to remove the lens, depending on the surgeon’s experience.
* Total lens aspiration works well for traumatic lens rupture and leftover lens matter after cataract surgery in certain types of glaucoma.
* In the case of fully or partially dislocated lenses, various techniques are applied depending on the severity of the dislocation.
Even if a patient’s vision is unlikely to improve, cataract surgery can still be done to control inflammation and pain.
For visual improvement:
* Using a posterior chamber intraocular lens (IOL) can be done if the posterior capsule is intact and stable.
* If a cataract is displaced, devices like capsule tension rings or Cionne rings help stable the bag to make it easier to implant a posterior chamber IOL.
* In the cases of complete or partial lens removal, an IOL that is either fixated to the sclera (the white part of the eye) or placed in the anterior chamber can be implanted, depending on the success rates. Eye drop medications are used to control eye pressure after surgery.
Treatment options for certain types of glaucoma could include lens extraction and trabeculectomy (a procedure that removes part of the eye’s trabecular meshwork to reduce pressure). Furthermore, in certain situations, cataract surgery or cyclodiode laser treatment could be considered to lower eye pressure.
What else can Lens-Induced Glaucoma be?
Acute angle-closure glaucoma (ACG) is a condition that can easily be mistaken for primary malignant glaucoma (PMG) or primary (or pseudo) exfoliation glaucoma (PLG). Knowing if there’s a family history of glaucoma or past experiences of similar episodes can help differentiate between them. An eye examination, called gonioscopy, of the other eye also helps determine the exact cause.
Ciliary block glaucoma (CBG), also known as malignant glaucoma or aqueous misdirection syndrome, occurs when there’s a buildup of fluid behind the front part of the eye. This condition is often confused with plateau iris configuration or syndrome (PBG). A treatment using laser to create a small hole in the iris (LPI) is used to diagnose as it can ease the PBG episode, but does not reduce the intraocular pressure (IOP) in cases of CBG.
Supra-choroidal hemorrhage is another condition that can be mistaken for PBG as it causes a flat anterior chamber (AC) and raised IOP. A detailed evaluation of the back of the eye (fundus evaluation) can show a dark red swelling that is typical with this condition. If the view of the back of the eye isn’t clear, an ultrasound can be performed to help diagnose the condition.
Choroidal effusion is a condition that normally presents with a low IOP. If the effusion affects the ciliary body and leads to secondary cyclodialysis, it can present with a raised IOP and a flat AC, similar to PBG.
After an eye injury, infection can occur which is known as post-traumatic endophthalmitis. Symptoms such as presence of pus in the eye (hypopyon), elevated IOP, corneal swelling, or an inflammation in the anterior chamber with a broken lens can mimic or occur together with primary angle closure glaucoma (PAG). To rule out endophthalmitis, a microbiological evaluation of the anterior chamber or vitreous fluid may be necessary.
What to expect with Lens-Induced Glaucoma
Seeking treatment promptly when symptoms first appear can greatly improve your chances of having a good visual outcome. This is especially true if the condition is managed early and if your eye pressure is well controlled while your lens is being removed. However, if the condition is not treated as a matter of urgency or is chronic, prognosis typically declines.
The development of peripheral anterior synechiae (PAS), a type of eye condition, tends to indicate a poor prognosis and the need for regular monitoring of intraocular pressure (IOP), which might involve medical treatment or surgery.
A combined procedure that includes the removal of the cataract and a type of eye surgery called trabeculectomy has shown to be effective in controlling IOP immediately after surgery. However, over the long term, the failure rate of the trabeculectomy part of the procedure tends to be high.
Possible Complications When Diagnosed with Lens-Induced Glaucoma
Lens-induced glaucoma can result in several complications such as:
- Persistent inflammation
- Deposits of pigment or protein on the artificial lens (IOL)
- PAS formation – a type of condition where the eye’s drainage angle is blocked, causing sealed glaucoma (synechial ACG)
- Continued high eye pressure despite glaucoma surgery
- Limited improvement of vision
- Glaucomatous optic atrophy – damage to the optic nerve due to glaucoma
- Endophthalmitis – inflammation of the inner eye
- Expulsive choroidal hemorrhage – sudden bleeding in the back of the eye
- Loss of vision
- Painful atrophic bulbi – the shrinking of an injured or diseased eye
- Phthisis bulbi – the end stage of eye disease resulting in a shrunken and nonfunctional eye
Recovery from Lens-Induced Glaucoma
Keeping a close watch on intraocular pressure (IOP) and gradually reducing the usage of medications that lower this pressure are essential in managing glaucoma. Regular checks of the back of your eye are advised, which usually involves tests called perimetry. After about 4 to 6 weeks, we might also recommend visual rehabilitation, where the focus would be on adjusting your glasses prescription for both near and far distances.
Preventing Lens-Induced Glaucoma
It’s crucial that children diagnosed with conditions related to EL get an early evaluation for the possibility of a shift in their eye lens. They should also have their eye pressure and light bending properties frequently checked.
Elderly individuals should be able to reach healthcare facilities easily. Regular screenings should be conducted for the emergence and progression of age-related cataracts. Treatment should be provided before the onset of MSC and related LIG. This preemptive approach ensures a better eye health management for older people.
