Under normal circumstances, the lens is suspended by the suspensory ligament directly behind the pupillary area and its axis is almost identical to the visual axis. Due to congenital, traumatic or other pathologies that cause the suspensory ligament to develop abnormally or rupture, the lens can be positioned abnormally and deviate from the visual axis, resulting in a series of visual symptoms.
I. Symptoms
High myopia
Due to the abnormality or rupture of the suspensory ligament, the lens, which is detached from the center of the visual axis, loses the pull of the suspensory ligament and becomes round in shape, increasing the refractive power, and therefore, patients may experience symptoms of high myopia.
High hyperopia
If the lens dislocation is large and far from the center of the visual axis, the refractive power of the lens in the visual axis area is lost, as if a lens is missing from the eye, and the patient may have symptoms of high hyperopia.
Monocular diplopia
Due to a shift in the position of the lens, one part of the optic axis area is refracted by the lens, while the other part is missing, making it appear as if there are two refractive systems in the same eye, resulting in monocular diplopia.
Ocular pain (secondary glaucoma)
If the deviated lens causes pupillary blockage, preventing atrial fluid from draining, secondary glaucoma occurs, resulting in red, swollen, and painful eyes.
A few issues you need to know.
1. Is high myopia necessarily caused by a dislocated lens?
No, it is not. High myopia is usually caused by the growth of the eye axis, and a few are caused by lens factors. Therefore, symptoms such as high myopia are not specific to lens dislocation, and the specific cause of high myopia can only be determined by combining medical history and physical examination.
2. Do symptoms such as high myopia, high hyperopia and monocular diplopia always exist at the same time?
No. Patients may have only one symptom or one symptom at a time. Patients may have only one symptom, or one symptom may predominate.
3.Does a deviated lens always cause glaucoma?
No, it does not. Many patients with a dislocated or subluxated lens only have visual symptoms without eye redness and eye pain. This is because the lens in these patients does not cause pupillary impingement that affects atrial circulation or stimulates the ciliary body to produce excessive atrial fluid, and glaucoma occurs.
Second, the disease
1. The concept of the disease is due to congenital, traumatic or other lesions that cause abnormal development or rupture of the suspensory ligament, which can cause the lens to be in an abnormal position and produce ectasia or dislocation. If the lens is not in its normal position at birth, it is called lens ectasia; if the position of the lens changes after birth due to congenital factors, trauma or lesions, it can be collectively referred to as lens dislocation or subluxation. However, it is sometimes difficult to distinguish when a change in the position of the lens occurs, so there is no strict demarcation between lens dislocation or ectasia, and it is often common.
2, the occurrence of the disease lens depends on its suspensory ligament and ciliary body connection and is maintained in a certain position, its position is abnormal for two reasons: one is trauma caused by the lens suspensory ligament rupture, and the other is congenital lens suspensory ligament hypoplasia or relaxation and weakness, both can lead to lens dislocation or subluxation.
A few things you need to know.
(1) Where is the normal location of the lens?
The lens is located behind the iris and is located right in the center of the visual axis area because of the balanced traction of the suspensory ligament all around 360°.
(2) Why is the lens displaced?
Since the lens is maintained in a certain position by the tethering of the suspensory ligament to the ciliary body, when the suspensory ligament is broken or relaxed, it can cause an asymmetry in the force of traction on the lens, causing the lens to shift in the direction of the stronger suspensory ligament.
(3) What factors can cause rupture or weakness of the suspensory ligament?
Specifically, there are the following three factors.
(1) Congenital lens ectasia or dislocation: This can occur as a congenital anomaly alone; or in conjunction with pupillary ectasia and other ocular anomalies or systemic syndromes. In either case, it is mostly due to weakness of the suspensory ligament of a part of the lens and the asymmetric force of the traction lens, causing the lens to shift in the direction of the stronger suspensory ligament force.
2, traumatic lens dislocation: eye trauma, especially blunt contusion is the most common cause of lens dislocation. Traumatic lens dislocation is often accompanied by cataract formation. A completely dislocated lens may dislocate into the anterior chamber or vitreous cavity.
Spontaneous lens dislocation: Spontaneous lens dislocation is caused by mechanical elongation of the suspensory ligament due to intraocular pathology, or due to inflammatory decomposition and degeneration.
3, the common reason for the delayed treatment of the disease as mentioned above, precisely because there are no specific symptoms of lens subluxation, it is often mistaken for other eye diseases or masked by the symptoms of other eye diseases, resulting in delayed diagnosis and treatment. For congenital lens dislocation, the diagnosis and treatment of lens dislocation is often delayed because parents do not pay attention to the symptoms of blurred vision or high myopia, or simply correct the lens without regular eye examinations, resulting in amblyopia; for traumatic and other spontaneous lens dislocations, symptoms such as high myopia are often masked by other symptoms of ocular trauma or other combined eye diseases, resulting in delayed detection and treatment. For traumatic and other spontaneous lens dislocations, detection and treatment are often delayed because symptoms such as high myopia are masked by other symptoms of eye trauma or other co-morbidities, which require careful examination by the doctor and good cooperation from the patient for follow-up to avoid.
A few things you need to know.
Does a subluxation or total dislocation of the lens require immediate surgery?
No, it does not. If the dislocation does not significantly affect vision or cause complications, surgery can be withheld and followed up regularly. However, it is important to note that a subluxation of the lens may block the pupil and lead to secondary glaucoma, while a total dislocation of the lens into the vitreous cavity may cause retinal detachment. Therefore, if the decision is made to withhold surgery, close follow-up is needed to detect relevant complications and intervene in a timely manner. Depending on the patient’s specific situation, some doctors may recommend early surgery to avoid serious consequences.
If the lens is fully dislocated into the anterior chamber, or if the lens is clouded or dissolved, or if serious complications such as glaucoma and retinal detachment have occurred, surgery should be performed promptly.
Interpretation of common misconceptions of the public.
(1) “If a child has high myopia, why go to the hospital for a checkup when you can just get glasses? It is time consuming and costly.”
This idea may cause delays in the treatment of certain diseases. It is not uncommon for young patients with high myopia to be seen in an ophthalmology clinic only to be found to have congenital cataracts or lens hemianopia. Therefore, parents should pay attention to their children’s severe refractive errors and undergo regular eye examinations to rule out other diseases.
(2) “I have an eye injury, but fortunately the eye is not broken and my vision should not be a big problem.”
This is a common misconception among patients in the emergency ophthalmology department. Many patients with ocular trauma may relax their follow-up and treatment or have high expectations for the prognosis because the doctor told them that the eye is not broken. In fact, even if the eye is not ruptured, blunt contusions can still occur and seriously affect vision, including lens dislocation, in addition to intraocular hemorrhage, secondary glaucoma, and so on. Therefore, follow-up visits should be conducted in accordance with medical advice to detect problems in time for timely intervention.
4. The common manifestations of the disease include high myopia, high hyperopia, monocular diplopia, secondary glaucoma and so on. In addition, patients with congenital lens subluxation may also be combined with congenital abnormalities of the eye or the whole body; patients with traumatic lens subluxation are combined with other manifestations of ocular trauma; patients with spontaneous lens subluxation are combined with other manifestations of concurrent eye diseases, such as inflammation, over-ripe cataract, intraocular tumor and other manifestations.
A few things you need to know.
(1) What ocular and systemic abnormalities can be combined with congenital lens ectasia or dislocation?
Congenital lens ectasia or dislocation can be classified into the following three types.
Simple lens ectasia: It is often symmetrical in both eyes and the exact mechanism is unknown. It presents as a simple abnormality of lens position without lens morphology or other ocular or systemic abnormalities.
With lens morphology and ocular abnormalities: spherical lens, lens defects, and aniridia are common.
Concomitant systemic abnormalities.
①Marfan syndrome: characterized by abnormalities of the eye, cardiovascular and skeletal systems. Ocular anomalies manifest as lens ectasia, especially upward and temporal displacement. The eyes may also have anterior chamber angle abnormalities, choroidal and macular defects, and may also produce complications such as glaucoma, retinal detachment, nystagmus, strabismus, and amblyopia. Skeletal abnormalities are seen in elongated bones in the hands and feet, long head and long thin face, non-closing of the foramen ovale of the heart, aneurysm and aortic stenosis. It is generally more common in males than females.
②Homozygous desmoplastic aciduria: most often affecting the bones, it is characterized by osteoporosis and a tendency to systemic thrombosis. The lens is more often dislocated subnasally and the lens is easily dislodged into the anterior chamber and vitreous cavity. The eyes may also be combined with congenital cataracts, retinal detachment and degeneration, absence of iris and other abnormalities. Laboratory tests may detect homocysteine in blood and urine.
(iii) Marchesani syndrome: short body, short and thick limb fingers (toes), normal cardiovascular system. The lens is spherical, smaller than normal, often dislocated inferiorly to the nose, and after dislocation, the lens enters the anterior chamber and is prone to glaucoma, often with refractive hypermetropia. Other ocular anomalies include ptosis, nystagmus, and microkeratoconus.
(2) What ocular manifestations can be combined with traumatic lens dislocation?
Traumatic lens dislocation is often caused by blunt contusion of the eye and can be combined with intraocular hemorrhage, retinal fissure, retinal detachment, secondary glaucoma, etc.
(3) What eye diseases can cause spontaneous lens dislocation?
Lens dislocation due to mechanical elongation of the suspensory ligament is commonly seen in dilated eyes, but can also be caused by inflammatory adhesions of the ciliary body or vitreous strips pulling on the lens. Intraocular tumors can push and pull the lens out of its normal position. Inflammatory disruption of the lens suspensory ligament is seen in endophthalmitis or total uveitis, where the suspensory ligament may completely disintegrate. Degeneration or dystrophy of the suspensory ligament is the most common cause of natural dislocation and is often accompanied by degeneration and liquefaction of the vitreous, as in high myopia, old chorioretinitis or ciliary stye, and retinal detachment. Gradual degeneration and disintegration of the suspensory ligament can also occur following ocular trauma such as iron or patina deposition. Another common cause is the overripe stage of senile cataract, where the degenerative changes of the lens also involve the lens suspensory ligament. Once the suspensory ligament degenerates, the lens can spontaneously dislocate at any time due to its own weight or minor trauma or even force and coughing.
5, the diagnosis of the disease is more obvious lens subluxation, pupil dilation can be directly seen in the slit lamp lens deviation from the center of the visual axis, exposing the edge of a side. Some occult lens subluxations are difficult to identify directly under the slit lamp and require special tests such as ultrasound biomicroscopy (UBM) to determine the position of the lens and the condition of the suspensory ligament. In addition, patients with lens subluxation need to be followed closely for intraocular pressure; patients with total lens subluxation into the vitreous cavity need to be monitored closely for retinal conditions; and patients with total lens subluxation into the anterior chamber need to be monitored for corneal endothelial damage and edema.
III. Treatment
Treatment of lens dislocation is difficult. Removal of the dislocated lens is more difficult and risky than normal cataract removal. Therefore, the treatment plan should be decided carefully. Treatment of lens dislocation depends on the position of the lens, the hardness of the lens, the visual acuity of the affected eye and the visual acuity of the opposite eye, age, the presence of congenital anomalies, the presence of complications, and the conditions for surgery.
If the lens is clear and does not cause complications, surgery may be withheld and glasses may be worn for correction with regular follow-up. If the dislocated lens is cloudy, dissolved, or causes serious complications, and if the dislocated lens is located in the anterior chamber or pupil, it should be surgically removed or excised, and an artificial lens should be implanted according to the patient’s eye condition.
A few issues you need to know about.
1. How to remove a partially dislocated or fully dislocated lens?
Different surgical options are available depending on the patient’s specific situation. The options are ultrasonic emulsion aspiration, extracapsular removal, intracapsular removal, transciliary flat resection, and incisional removal at the anterior chamber corneal edge.
2. How is the IOL implanted?
Since patients with lens subluxation or dislocation no longer have a stable stent for IOL placement, IOLs cannot be implanted directly into the lens capsule as in conventional cataract surgery. The most appropriate surgical approach should be chosen based on the patient’s specific situation. The options are capsular bag tension ring combined with IOL implantation, iris clip IOL implantation, IOL scleral suture fixation or iris suture fixation, anterior chamber IOL implantation, etc. The principle of choice is to ensure the stability of the IOL.
Common misconceptions among the public explained.
”The doctor should implant an IOL immediately after removing my subluxated lens.”
This is not entirely true. Some patients with severe lens dislocations should not have an IOL implanted in a single procedure. This is because, in these severely dislocated patients, there is no stable IOL scaffold at all after lens extraction and more complex IOL implantation procedures such as scleral suture fixation are required. If these two procedures are performed simultaneously, they are often more damaging, have a significant surgical response, and may cause serious surgical complications. Therefore, for patient safety reasons, lens removal and IOL implantation are often performed separately.
6. The prognosis of the disease is closely related to the cause of lens dislocation, concomitant diseases, and other ocular conditions, and varies greatly among individuals. The causes of vision loss due to lens dislocation are multiple, such as refractive interstitial clouding, secondary glaucoma, congenital fundus abnormalities, etc. Therefore, lens removal does not necessarily improve vision.
Common misconceptions among the public are explained.
”If you have had surgery, your vision will be restored.”
This is a misconception. On the one hand, there are many factors that affect vision in patients with lens hemianopia, and surgery is only one of them; on the other hand, the surgery itself is difficult and risky. Therefore, it is a misconception that “vision can be restored after surgery”. It is important to understand that lens subluxation requires comprehensive treatment in many aspects, and the prognosis of different patients also varies greatly.
For patients with lens dislocation into the vitreous cavity, or even retinal detachment and other complications, they should be referred to a fundopathologist. For patients whose lens has prolapsed into the anterior chamber and has caused corneal endothelial loss and corneal edema, they can be referred to a keratologist for further consultation after the lens has been removed.
A few questions you need to know.
What is corneal endothelial loss?
Damage to the corneal endothelium is not renewable. If the lens is prolapsed into the anterior chamber for a longer period of time and severely damages the corneal endothelium, resulting in a severe loss of endothelial function, it can lead to irrecoverable corneal edema and the patient experiences vision loss, eye pain and photophobia. At this time, the keratoconologist is required to carry out the appropriate treatment, including corneal endothelial transplantation, penetrating corneal transplantation, etc.
8, patients and doctors lens dislocation is a relatively difficult disease to treat, more need for communication and mutual understanding between doctors and patients. Doctors should give full explanation and patients should understand the riskiness and uncertainty of the prognosis of surgery for this disease and should not equate it with general cataract surgery.