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Lens abscess or intralenticular abscess is a rare ocular pathology seen after blunt or penetrating ocular trauma, routine cataract surgery, or metastatic infection. The patient usually presents with pain, redness, and acute reduction in visual acuity. On slit lamp examination, it appears as heterogenous lenticular opacity. It is imperative to delineate the abscess and remove it from the capsular bag to prevent chronic endophthalmitis. It is also necessary to differentiate lens abscesses from traumatic cataracts as the management and prognosis differ in the two cases. The tools available to diagnose a lens abscess are ultrasound B scan, anterior segment optical coherence tomography (ASOCT), and ultrasound biomicroscopy (UBM). The management of these cases is lens aspiration as soon as possible to remove the infective foci. Objectives: Describe the etiology of lens abscesses. Review the pathophysiology of lens abscess. Summarize the differential diagnosis of lens abscess. Outline the management of lens abscesses. Access free multiple choice questions on this topic.

Intralenticular or lens abscess is an uncommon ocular entity resulting from post-trauma, surgery, or metastatic spread.[1] It can also be sterile. Lens abscesses can result secondary to trauma from iron rod, thorn injury, vegetative matter trauma, intralenticular cilia or ophthalmia nodosa, mud injury, dust fall, and stone injury and can also result from blunt trauma to the eye. The lens can be damaged in approximately 30% of perforating eye injuries and 10% of intralenticular foreign bodies lodged in the lens.[2] In cases with blunt trauma, the patient with a lens abscess can have mild symptoms such as pain, blurred vision, and watering. The patients with penetrating trauma present with pain, redness, and sudden onset defective vision.[3] Slit lamp examination usually reveals a heterogenous lens opacity or pus-filled lenticular cavity. Fundus examination is extremely vital to rule out vitritis and endophthalmitis. Documentation of visual acuity, intraocular pressure, and seidel's test is also essential to assess the treatment response in each case. The other critical investigation of interest which can delineate a lens abscess well are ultrasound B scan, anterior segment optical coherence tomography (ASOCT), and ultrasound biomicroscopy (UBM).[4] It is also essential to assess the integrity of the posterior capsule as the risk of endophthalmitis is increased manifold when the posterior capsule is ruptured. It is vital to differentiate lens abscesses from traumatic cataracts, as IOL implantation in primary sitting is contraindicated. Diagnosing lens abscess requires clinician expertise, experience, and a high index of suspicion. Prompt diagnosis, targeted intervention, elimination of microbial load, and regular and meticulous follow-up are the key elements for treatment success. It is also important to take a culture from the lens aspirate to pinpoint the microorganism. In cases with fungal lens abscesses, intravitreal steroids should be avoided. A detailed examination and high clinical suspicion are required to look for complications like secondary glaucoma, cystoid macular edema, and endophthalmitis.[5]

Bacterial Staphylococcus Aureus Staphylococcus is the most common bacteria on the ocular surface and is an aerobic gram-positive organism with low virulence. It can also enter the after penetrating through an exogenous source. The organism is also commonly seen in the aspirate cultured from lens abscess.[6] Staphylococcus Epidermidis Staphylococcus epidermidis is also an aerobic, gram-positive bacteria with low virulence. It is commonly seen as a commensal in the eyes or can be associated with postoperative endophthalmitis. The organism has also been cultured from lens aspirate of lens abscess. There can also be a delayed manifestation of postoperative infection because steroids and antibiotics usually mask the initial response. As per previous reports, the microorganism can adhere to the plastic surface of the intraocular lens by producing a glycocalyx polysaccharide which acts as a glue.[7] Propionibacterium Acne Propionibacterium acne is commonly seen on the skin and conjunctiva and generally can be considered a contaminant of the ocular surface. The microorganism is an anaerobic, Gram-positive rod, which can also result in a mixed eye infection. The organism is sensitive to penicillin, less sensitive to cephalosporins, and resistant to gentamicin and vancomycin. The microorganism has also been reported commonly from lens abscess, postoperative endophthalmitis after trabeculectomy, and keratoplasty. It also invites the development of phacoantigenic uveitis.[5] Stenotrophomonas Maltophilia This microorganism has also been reported in cases with lens abscesses.[8] Paecilomyces Lilacinus This is one of the rare species reported in lens abscesses.[9] Streptococcus Pneumoniae (Pneumococcus) Pneumococcus causes ulcus serpans and has also been cultured in cases with lens abscesses.[10] Pseudomonas Aeruginosa This is another species reported from lens abscess.[11] Fungal Aspergillus niger Candida Bipolaris Cladosporium Unidentified hyaline fungi[12]

Lens abscess is more common in males because most are outdoor workers, especially farmers and factory workers. The lens can be damaged in approximately 30% of perforating eye injuries and 10% of intralenticular foreign bodies lodged in the lens.[13]

Once the anterior lens capsule is breached secondary to penetrating or blunt trauma, there is a cortical disturbance. The displaced cortex acts as an excellent nidus for microorganisms' growth and infection eruptions.[14] This results in the lenticular cavity or lens abscess. Since the lens is avascular, topical antibiotics also don't reach the lens cavity directly. It has also been observed that if the anterior capsular tear or rupture is less than 2 mm, it can heal without the proliferation of lens epithelial cells. Intraocular foreign bodies in the lens can also act as a nidus for microorganisms.[1] Sometimes the foreign body is inert and remains lodged in the lens substance without reaction. If there is a breach of the posterior capsule, the microorganism, retained lens cortex, lens abscess, and chemical toxins released by the microorganism can reach the vitreous cavity and result in an inflammatory cascade.[15] This results in vitritis and endophthalmitis. Whenever there is delayed endophthalmitis by low-grade pathogens such as P.acne, this is called localized endophthalmitis. In cases with immunosuppression or immunosuppressed patients, the mechanism of ocular immune privilege is also compromised in the anterior chamber, with a disrupted blood-retinal barrier, immunosuppressive factors in the eye, and systemic immune compromise such as anterior chamber-associated immune deviation (ACAID).[16]

History A detailed history is extremely vital in each case. There can be blunt or penetrating trauma. There can be a history of vegetative matter trauma, needle, fishhook, iron rod, caterpillar hair, stone, mud, clay, metal, and chestnut injury.[17] Symptoms The patient can present with blepharospasm, swelling, pain, redness, defective vision, watering, photophobia, floaters, and flashes.[18] Signs Anterior segment examination may reveal any of the signs such as conjunctival congestion, chemosis, subconjunctival hemorrhage, conjunctival tear, corneal lamellar tear, full thickness cornea tear, self-sealed corneal tear, corneal edema, anterior chamber hypopyon, cells and flare in the anterior chamber, exudates over the iris, iridodialysis, iris bombe, posterior synechiae, relative afferent pupillary defect, sluggish reacting pupil, lens neovascularization,  pus-filled lens, or lens abscess. Sometimes the lenticular opacity can take the appearance of yellow-white exudate.[3] The classic description of a lens abscess is whitish-yellow, dense, homogenous lenticular opacity which is well demarcated from the remaining lens. There can be an injury to the posterior capsule resulting posterior capsular tear. There can be associated vitritis, vitreous membranes, retinal injury, retinal tear, choroidal detachment, and exudates. There can be the associated presence of the foreign body in the anterior or posterior segment.[19] Intralenticular abscess after fungal infection is less common. In cases with lens abscess due to fungal etiology, the typical findings are uveitis, fungal balls, and fibrinous membrane over the pupil. Fungal lens abscess can also manifest as fungal endophthalmitis, a latency of weeks to months. The timing of symptoms can vary from 24 hours to 6 months post-trauma, with an average of 1.8 months after open globe injury. In fungal endophthalmitis, the symptoms are subacute, and they worsen gradually.[20] P.acne can also cause acute endophthalmitis, which can present as a full-blown acute infection or chronic low-grade smoldering infection. Chronic endophthalmitis has to be differentiated from phacoantigenic uveitis. In each case of lens abscess, it is essential to document the nature of trauma, presentation duration, onset and severity of symptoms, clinical findings, and visual acuity.[21]

Seidel's Test In cases with blunt or penetrating trauma, it is always necessary to perform the Seidel and forced Seidel tests to determine the aqueous leak. In case of an aqueous leak, it is mandatory to suture the tear.[22] Anterior chamber Tap An anterior chamber should be performed to pinpoint the microorganism from the aqueous aspirate. An aqueous tap can be performed from the paracentesis with a 25 G needle, and 0.1 ml of aqueous can be aspirated for analysis.[23] Smear Analysis The lens material can also be taken on KOH smear, Gram stain, and Giemsa stain to determine whether it's a bacterial cause or a fungal cause.[24] Culture of Lens Aspirate In cases with the anterior capsular breach and cortical disturbance, the lens material can be removed by either lens aspiration by bimanual irrigation and aspiration or extracapsular cataract extraction approach or by manual small incision cataract surgical approach. Some of the lens material should be sent for culture, which can reveal colonies of a microorganism after 72 hours of growth. The most common culture media used are blood agar, chocolate agar, MacConkey agar, and Sabround Dextrose agar incubated in bacteriological indicator for 16 hours overnight at 37 degrees Celsius.[25] B Scan Ultrasonography This is a valuable investigation to rule out vitritis, vitreous membrane, exudates, endophthalmitis, and vitreous hemorrhage. When there is a defect in the posterior capsule, the lenticular matter can be seen extruding through the posterior capsule in the vitreous cavity as a dumbbell. This is called a "dumbbell sign" of lens abscess.[26] Anterior Segment Optical Coherence Tomography ASOCT is a vital tool for looking for lens abscesses. It appears as heterogenous lenticular opacity on ASOCT.[1] Ultrasound Biomicroscopy UBM has also been listed as a vital tool for delineating lens abscesses.[27] Computed Tomography CT scan is vital to localizing any occult foreign body and bony defects.[28]

Medical Management Antibiotics Antibiotics are the mainstay in managing lens abscesses and safeguarding the eye from endophthalmitis. They can be given as topical, oral, intravenous, subconjunctival, and through the intravitreal route. They help in controlling infection and prevent the spread of abscesses.[29] Topical The drugs implicated are Moxifloxacin 5 mg/ml Fortified tobramycin 14 mg/ml Cefazolin 50 mg/ml Gentamicin 13.6 mg/ml Cefuroxime 50 mg/ml[30] Subconjunctival Cefazolin 100 mg Gentamicin 20 mg Cefuroxime 125 mg Amphotericin B injections 0.01 mg/0.1 cc[31] Intravenous Cefazolin sodium Gentamicin Sulphamethoxazole 240 mg Trimethoprim 1.2 g[32] Intravitreal Ceftazidime 2 mg Vancomycin[33] Oral Flucloxacillin 250 mg Pivampicillin 500 mg Metronidazole 400 mg Ofloxacin 200 mg Imipenem 200 mg[26] Antifungals Lens abscesses can also result from fungal species; hence topical, oral, and intracameral antifungals are needed. Topical antifungals have a slower penetration. Accordingly, hourly administration is warranted to get adequate anterior chamber penetration.[34] Topical Natamycin 5% Voriconazole 1% Itraconazole 1%[35] Oral Fluconazole 150 mg Voriconazole 200mg[36] Intracameral Voriconazole 0.1cc[37] Intrastromal Voriconazole 0.1 cc[38] Corticosteroids Corticosteroids are the mainstay in controlling inflammation. They should be used only when the infection has been controlled. The treating surgeon should be cautious while starting the steroids as it may flare up the abscess and vitritis and lead to the rapid multiplication of microorganisms leading to endophthalmitis. The postoperative steroid regimen is continued after cataract extraction, lens aspiration, and IOL implantation. They can be given through topical and oral routes. In rare cases, if there is persistent posterior segment inflammation, steroids are needed through intravenous and intravitreal routes. Topical steroids help treat conjunctival and scleral inflammation. Steroids can suppress the host's immune system, leading to deeper penetration and proliferation of the fungus. This can result in rebound anterior segment inflammation.[39] Topical Prednisolone acetate 1% 10 mg/ml Dexamethasone 0.1% Betamethasone 0.05%[40] Adjuvant Drugs Cycloplegics Cycloplegics help to control anterior chamber inflammation, relieve ciliary spasms, relieve pain, break posterior synechiae, prevent the formation of synechiae and prevent the breakdown of the blood-aqueous barrier. They are vital in controlling inflammation.[41]

Dexamethasone 0.1% Betamethasone 0.05%[40] Adjuvant Drugs Cycloplegics Cycloplegics help to control anterior chamber inflammation, relieve ciliary spasms, relieve pain, break posterior synechiae, prevent the formation of synechiae and prevent the breakdown of the blood-aqueous barrier. They are vital in controlling inflammation.[41] Drugs Implicated Atropine 1% Cyclopentolate 1% Homatropine 2.5%[42] Antiglaucoma Drugs They are needed to control intraocular pressure from uncontrolled inflammation, trabecular meshwork blockage, and trabeculitis. Miotics and prostaglandins are contraindicated in ocular inflammation. Drugs Timolol 0.5% Brimonidine 0.2%[43] Surgical Management Evacuation of Lens Abscess Whenever there is a breach in the anterior capsule and cortical matter disturbance, the lenticular material should be removed immediately to prevent endophthalmitis and panophthalmitis.[1] Lens Aspiration Young patients have no nucleus with lens matter, and the lenticular matter is mostly cortical. Hence the lens material can be easily aspirated from the paracentesis using bimanual irrigation and aspiration.[44] Extra Capsular Cataract Extraction (ECCE) In today's era, ECCE is not practiced much but is a viable option for abscess removal through the superior limbal incision.[45] Manual Small Incision Cataract Surgery (MSICS) Another nuclear management option is MSICS, by performing a sclerocorneal tunnel for cataract and abscess removal.[46] Phacoemulsification Those surgeons who don't practice ECCE and MSICS can use phacoemulsification as the primary process for lens removal.[47] Anterior Vitrectomy In some cases where there is zonular dialysis and posterior capsular breach, vitreous prolapse occurs in the anterior chamber. These cases require automated anterior vitrectomy along with the primary procedure.[48] Pars Plana Vitrectomy In cases where there is a nucleus drop, cortical matter drop in the vitreous cavity, non-resolving vitritis, vitreous hemorrhage, and endophthalmitis will require a para plana vitrectomy along with pars plana lensectomy or vitreous lavage.[49] Aphakia Management

In some cases where there is zonular dialysis and posterior capsular breach, vitreous prolapse occurs in the anterior chamber. These cases require automated anterior vitrectomy along with the primary procedure.[48] Pars Plana Vitrectomy In cases where there is a nucleus drop, cortical matter drop in the vitreous cavity, non-resolving vitritis, vitreous hemorrhage, and endophthalmitis will require a para plana vitrectomy along with pars plana lensectomy or vitreous lavage.[49] Aphakia Management Earlier aphakia management was a matter of debate in cases of lens abscess. Primary IOL implantation reduces the visual rehabilitation time and defers additional surgical procedures. However, it is always advisable to defer primary IOL implantation in these cases. Primary IOL implantation can cause severe uveitis and manifest as cells, flare in the anterior chamber, keratic precipitates at the back of the cornea, posterior synechiae at the back of the cornea, pigments on the IOL, and vitritis. Secondary IOL implantation as a staged procedure has good outcomes in these cases and prevents developing infection and inflammation. A 3-piece hydrophobic IOL is stable for these cases.[50] Nd YAG Laser Capsulotomy Nd YAG laser capsulotomy will be needed once posterior capsular opacification is developed. This should be attempted only after three months of quiescence.[8] 100% Oxygen The administration of 100 percent oxygen has also been tried as a treatment for lens abscess.[46]

Bacterial keratitis Fungal keratitis Pythium keratitis[51][52][53] Acanthamoeba keratitis Endophthalmitis Panophthalmitis Bechet's disease HLA B27 associated uveitis Traumatic cataract Panuveitis

Prognosis in lens abscess cases depends on multiple factors such as type of trauma, the onset of infection, anterior or posterior segment involvement, immune status, timing and nature of the treatment, follow-up, and patient compliance.[1] The prognosis is good if the lens abscess is evacuated immediately and the posterior capsule is intact. The intact posterior capsule prevents the spread of infection to the vitreous cavity and acts as a barrier to the development of vitritis, pan uveitis, and endophthalmitis.[54] The prognosis is poor if the posterior capsule is breached, the posterior segment is involved, and the immune system is compromised. Delay in surgical intervention is another reason for the poor prognosis of these cases.[54]

Amblyopia Corneal scar Corneal decompensation Secondary glaucoma Festooned pupil Posterior synechiae Occlusio pupillae Seclusio pupillae Intermediate uveitis Panuveitis Vitritis Vitreous membranes Cystoid macular edema Endophthalmitis Panophthalmitis Retinal detachment Choroidal detachment

Any case of blunt or penetrating trauma presenting to the routine outpatient should be evaluated meticulously to rule out lenticular trauma and the development of an abscess. All patients should be dilated for lenticular examination, and the clinician should be able to differentiate between traumatic cataracts and lens abscesses. These cases should be referred to the cornea clinic or the available cornea consultant for expert inputs and targeted management. A retina specialist should also evaluate all lens abscess cases to rule out posterior segment involvement and prevent the development of any complications.[50]

All patients with a lens abscess should be counseled in detail regarding the nature of ocular pathology and its complications if not managed on time. The patient should be explained the need for lens abscess evacuation and aphakia management. The patient should also be explained that the primary aim is to get rid of the infection, and the secondary aim is visual rehabilitation. Each patient should be clearly explained the prognosis,  need for regular follow-up, timely treatment, and staged interventions.[50]

Lens abscess is a rarely reported entity in literature. For an astute clinician, it is essential to differentiate traumatic cataracts from lens abscesses as the treatment is poles apart. The prognosis in each case is governed by immune status and posterior segment involvement. If the posterior capsule is breached, there is a high chance of endophthalmitis. Topical antimicrobial therapy and steroids should be used based on the patient's clinical status. Surgical removal of the infective foci is the treatment of choice for lens abscesses.[50]

Lens abscess is a rare clinical entity usually diagnosed only by an experienced cornea or a cataract surgeon. Surgeons play a crucial role in diagnosing and managing these cases. The nurses help recruit the patient to the clinic, assist in slit lamp evaluation, visual acuity evaluation, intraocular pressure management, staining the eye, and counseling the patient.[57] They also help explain the medications to the patient and provide regular follow-ups of these patients. The pharmacist help in arranging the drugs for the patients. The operating room assistants help prepare patients during surgery and meticulously manage these cases. Hence, a good outcome in these cases depends on the interprofessional team's coordinated efforts and open communication between all team members.[58]