Soft Contact Lens Complications Lecture 6 PDF

Soft Contact Lens Complications February 2024 Epithelial & Stromal Edema Superficial & Stromal Vascularization Microbial Keratitis Fungal keratitis Acanthamoeba keratitis 1 Get lenses that have 30-40% water content Instead of fitting them with cl that have mid 50% water contact Every lens you put in...

Soft Contact Lens Complications February 2024 Epithelial & Stromal Edema Superficial & Stromal Vascularization Microbial Keratitis Fungal keratitis Acanthamoeba keratitis 1 Get lenses that have 30-40% water content Instead of fitting them with cl that have mid 50% water contact Every lens you put in the eye will dehydrate the eye based on their environment, less blinking with the intensive work Lenses that have higher water content will lose greater percentage of the water content and those with lower water content will lose lower percentage of the water content and not have much changes in comfort à meaning less dehydration, less steepening of the bc Silicon hydrogel vs hydrogel is the silocone content 1 Ideal Contact Lens: Does it Exist? Patient Ideal CL Immediate lens comfort Excellent vision Ultimate convenience of indefinite lens wear Practitioner Ideal CL Bio-compatibility 2 They provided clear vision initially and the comfort was not good so patient did not use it overnight With softer lens à the goal was to not take off the eye When soft lenses became available lasik also became available à The goal was bicomotability to not create inflammation and adverse affect Post refractive surgery was not ideal because after the surgery the cornela nerves are severed which can lead to dryness so medication to support tear production and topical lubrication may be needed 2 Is Refractive Surgery Ideal? NO Post refractive surgery dryness Higher order abberations (coma & Trefoil) Above -6.00 correction requires small 6mm corneal treatment zone, peripheral cornea is normal curvature creating night time peripheral blur as pupil dilates 8.0mm, beyond the treatment zone Presbyopia à they don’t want to wear glasses so they may need to go back for retreatment but with retreatment the results are less predictable Post Refractive Surgery Ectasia à2% of the patients – the thinning of the cornea destabilizes the cornea and the cornea continues to thin and becomes distorted and they wont see well with glasses à so they may need therapeutic cl due to the extasia Post surgical flap displacement problems à they can have displacement of the flap so the flap can be peeled away or displaced and need to be corrected again 3 Abberration can be a result of surgery as well which is not issue with contact lens For ppl who have more than -6.00, Treatment zone is small and those ppl whose pupil zone dilate to 8mm à have halos and blur around the vision at night 3 Early 1980’s Hydrogel SCL Patient Expectations + immediate comfort +/- clear vision DW success, No- EW FDA approval, YET EW & CW, Noncompliance ends up with complications (lens care, replacement, overnight wear) Practitioner Expectations DW bio-compatibility EW & CW, Noncompliance results in complications. 4 4 1981 EW Approved of Hydrogels Patient Response Practitoner Response cheers 5 5 1987 Disposable SCL Motivated by Practitoners & Industry (automation) Goal: Reduce Complications – Reduce wear of coated lenses (GPC, dryness, blur) – Reduce wear of bacterial contaminated lenses Frequency of Replacement – 3 months – 1 month – 2 week – DD Made possible by improvements / automation in 6 manufacturing & expanding Rx. FDA approved EW low DK lenses that they could sleep with Hydrogel lenses do not provide oxygen to allow overnight wear and patients had red eyes so hydrogel lenses should not be approved for ew where you can sleep 6 Disposable SCL-Patient Response / Outcome Ultimate in convenience (reduced solutions / cleaning) Eliminate / reduce exposure to preserved soln Increased cost of lenses lead to noncompliance with replacement schedule Positive reduction of red eye events in compliant DW patients Non-compliance still results in potentially serious corneal complications DD patient still experience end of day dryness7 7 More Frequent lens Replacement or Hydrogel Lenses Not the Total Answer when it comes to red eye events DD lens wearers can experience end of day dryness DD wearers can experience Red eye events DD wearers can be non-compliant 8 8 1998 Introduction of SiHY SCL Patient Perspective Immediate lens comfort Excellent vsion Convenience (disposability) EW & CW indefinite wear time ???? Practitoner Perspective Biocompatibility ???? Caution with EW Relief with Approved CW for therapeutic purposes that meet the research reported DK of 125 x 10-9 9 SIHI lenses meets the dk needed for less or not more edema that we exp at closed eye state (3.2%) Sihi lenses that met this criteria will provide the need for ew and continoues wear but it did not work 9 Improved O2 Transmission at thinnest portion of lens Lenses with significant improved DK – Some lenses meet 125 x 10-9 to avoid > 3.2% edema Frequent Lens disposability DK published is for -3.00, What about DK/t for range of Rx’s ??? What about Dk/t at thickest portion of lens?? What about wettability ?? What about Mucin balls ?? What about exchange of post lens tear film 10 DK value is -3 and the thickness that is used for dk/t à the thickness is defined by the optical zone of the lens Dk/t for -3 lens in the central optic zone to -10 lens was not equaivalent Higher the minus power – thicker the otpic zone is and the less oxygen that gets through. For instance a prism ballest lenses has thick edge and it can reduce oxygen transmission. Plus lenses à center thickness increases which means less transmission of oxygen centrally so we need a way for the oxygen to get through to allow enough oxygen to get there Post lens tera film exchange is 1-2% of exchange takes place per blink and is it enough to provide enough oxygen transmission when pt wearing higher rx à no 10 1998 FDA, Europe, Australia Create “Adverse Event Panel of International Society of Contact Lens Research” agree upon Definition of Adverse Ocular Events effort to track serious events based on severity of condition level of clinical concern clinical outcome from event 3 Categories Non-significant Adverse Events Significant Adverse Events Serious Adverse Events 11 There are many adverse affect that took place sihi equivalent to that of hydrogel lenses. Going to a higher permeable of oxygen lenses does not guarantee a pt not having red eye event this is because à lens thickness varies throughout the lens so the published data and oxygen delivery is not as accuracte Dk values of low powred lenses are published and the lens thickness varies throughout the peripheral regions Lens movement overtime à the movement may not be consistent or more/less so you need to consider that Whether there is sihi or hydrogel for the period of lens wear time à if the lens has tightened up and there is no movement means the waste product of the epithelium has stuck there behind the lens, there is no removal of the waste product and there is not transfer of oxygen and nutrient behind the lens Things can be trapped under the lens which may cause the irritation and lead to red eye events if the pateints does not know how to remove it 11 They came up with 3 categories of adverse affect Solution adverse affect à soleution reaction is non-significant adverse affect 11 Defintion of Adverse Events Non-Significant Adverse Event – Not of sufficient clinical concern – Ex: asymptomatic infiltrates, mild corneal neo, solution senitivity – They happen frequently and they dont share this with you because they dont suffer from this as much Significant Adverse Event – Of sufficient concern to warrant temporary or permanent d/c cl wear – Ex: CLARE, CLPU, GPC, Epi erosion, Viral, infiltrative keratitis, Sup Epi Arcuate Lesion (SEAL) à they feel light sensivtiy and they will want to know what to do Serious Adverse Event – Potential for significant visual impairment, permanent D/C of cl – Ex:Microbial, Fungal, Acanthamoeba keratitis. 12 Infiltrates à PMNs being delivered to the area of injury since the eye perceives there is problem in the specific location à they are asymptomatic but you notice the infiltrates you should ask the patients about red eye events and the pt may say no à the reaction of infiltrate was insignificant maybe due to soleution sensitivity so you need to document the number of infiltrate Mild cornela neo à they have increased vascularization of the limbal corneal area à wearing cl or due to solueiton sensitivity We treat the significant and serious because theu are serious and sight threatening à you treatment plan would be discontinue cl for days/weeks to see changes in ocular health or in extreme cases permenant discontinue Serious is very sight threatening and they may need corneal specialitst since it includes cornela infection 12 Fortunately, Most of what we see are Non & Significant Adverse Events Non-Significant: – Poor fitted CL – Solution sensitivity Significant: – Corneal edema – CLARE, CLPU, GPC, Erosions, Viral, Infiltrative, SEAL 13. 13 The Cascade of events that Can Lead to “Significant” Corneal Adverse Events Limbal vascular Hyperemia (early Hypoxia) Epithelial Haze (early Hypoxia) Epithelial Microcycsts (persistant Hypoxia) Reduced Epithelial Adhesion (persistant Hypox Stromal edema (chronic Hypoxia) Endothelial Cell loss (Chronic Hypoxia) 14 In soft cl wear and scleral wear you don’t really see endo loss and it tends to be opacified cornea due to surgical trauma where the endo cells get affect 14 Corneal Hypoxia: Changes Epi cell function & Structure Acute Hypoxia changes epi cell function – Aerobic metabolism becomes anaerobic metabolism (hyperemia progresses to neo-vessel growth) – Increased fluid retention (edema)(rainbow effect) – Slowing of cell migration from limbus to central cornea, – depression of basal cell proliferation à wound healing is slower – Depression of surface cell shedding – can be due to just blinking – Increase in cell surface residence (aging of epi cells) Age of the epi cell incrases and the older ones are fragile and can slough off easily even due to eye rubbing – Increase in cell fragility & decrease cell adhesion 15 The lack of oxygen can cause changes in epi cell and function As the epi layer suffers from hypoxia it goes from aerobic metabolism to anaerobic and there is also fluid retention… 15 Case 1: Red Eyes 20 yoM College student Prior Hx Acuvue 2 DW 4 yrs success Urgent Visit Hx Acuvue 2 Sx Red eyes. White & Quiet Bulbar OU 360 degrees Bulbar Injection Excellent comfort Va 20/20 Slight tearing,burning VA 20/25 16 The lens is less expensive and it is very old Moist lens is the same material as the accuve 2 When she took the cl off, she had increased tearing and her eyes were more uncomfortable and there was bruning/redness 16 Signs: Case #1 Signs – Onset 1-2 months – constant mild bulbar injection OU 360 – Constant mild tearing OU – Va now 20/25 OD & OS – PERRLA Symptoms.Constant mild tearing OU – Worse when lenses off Minimal lens awareness Worse comfort longer lenses are off the eye. FW/EW for past 1-2 months Prev DW was successful 17 She was wearing the lens on a monthly basis She wasn’t taking lenses off She had more discomfort with the lenses off and fb sensation with the lenses off It’s the shift from dw to fw to ew made the problem worse It was a tight fit since there are congested vessels beyond the cl and the vessels under the lens are normal in appearance. The edge is so tight that as the blood goes to superficial conj vasculature the blood goes to the edge of the lens but cannot go under the lens so blood flow backs up and becomes congested beyond the lens. There is no exchange of nutrients getting into the epi so the epi tissue gets disrupted 17 Stage 1: Mild Epi Edema: Limbal Vascular Engorgement Cornea is “Calling for Help” Limbal Hyperemia earliest clinical sign of a reduction of oxygen Patient is wearing a Hydrogel lens with early success Shift to FW/EW and onset of limbal vessel engorgement indicate mild hypoxia Corneal nerve sensitivity is reduced with anoxia, so minimal discomfort Discomfort more pronounced the longer 18 lenses have been off the eye. Why??? she is wearing the lenses months and longer She had limbal vessels engorgement à beyond the edge of the lens there is increased hyperemia and under the lens, the vessels are not engorged but beyond the lens the vessels are thickened 18 Fluorescein Assessment of Epithelial Precursor to corneal neovascularization Symptom of Mild dryness, increase w/o wear Mild Diffuse punctate staining due to ____? Short term effect? Long Term effect? Treatment options? – 1._______ – 2._______. 19 This was her cornea with the fluorescine in the eye With the lenses off, there is increased tearing, burning and fb sensation à there is wounded epi under the lens and with the contacts on she felt better as it acted as abandage on top Her mistake was switching to ew and not taking the contacts off. She needs to get through the discomfort so the cornea can heal itself. Recommend PF Ats because preservatives can contribute to the harm. Discontinue lens wear. We can also give prophylaxis antibiotics such as erythromycin since she has bad epithelium and it can cause infection We can give nighttime ointments à it provides better comfort, it will worsen the vision but the viscosity fo the ointment will give comfort and the gel will bathe the tissue overnight so when she opens her eye in the morning she doesn’t remove the fragile epithelial cells. 19 Stage 2: Limbal Vascularization If hypoxia is not resolved = Chronic edema Engorged superficial vessels cross limbal translucent zone, travel 1 mm into peripheral cornea Tortuous, angry New vessels leak White blood cells (PMN) creating mild inflammation Hazy cornea surrounding vessels If hypoxia resolved vessels become ghosts ready to refill if stress returns 20 If she was not compliant and she decided to continue with the ew lenses then there will be growth of the limbal vessels into the adjacent clear cornea and the vessels will travel 1mm into the peripheral cornea Have a beam of light and try to quantify how far into the cornea the vessels progressed. Focus the beam of light where the cornea meets the edge of the limbus The vessels are new so they tend to respond to the deficient of the oxygen the epi is looking for so the vessels are torutuous and the surrounding corneal cells tend to be hazy When the pt becomes compliant and the fit is beeter, the blood will retract out of the new vessels and they will be ghost vessels. You can see lumen of the vessels without blood travelling through but these vessels can easily refill if there is a new injury to the eye so you need to tell as you dispense higher dk lens and check if thye are still ghost or reactive vessels 20 Biomicroscopy ? 21 The vessels extended 1mm into the cornea and the area surrounding the vessels (cornea) look less clear as a result of the hypoxia because it is responding with a inflammatory response to allow neovasuclariztaion and part of the process is to take care of any insult to allow wbcs leak out of the vessels making this area look more unclear Along the 1mm extension fo the vessels in the every clock position aprund the cornea, there is hazing of the adjacent corneal surface 21 Biomicroscopy ? 22 22 Stage 2: Treatment Temporary D/C lens wear Refit into high DK lens, frequent replacement DW only Possible BC change to Improve lens movement Advise patient that if vessels continue to progress may need to refit into GP lens (if vessels 3mm into cornea) 23 We would use ats and lubricants to settle it down When the cornea has calmed down we go into the high DK value, limit it to DW wear, you can loosen the fit since the prev lens was tight and a flatter bc will allow more lens moevemnt. Introduce the idea to the pt that if this does not get improved then we might have to GP lenses à to show that if thye are not compliant we will start to take choices away from them Introduce the idea that if this continue to get worse they may need to get GP lens à typically this is is done if the vessels are 3mm into the cornea because otherwise the vessels can cross the visual apex and they will end up losing the quality of vision if they continue the non-complaint way or the situation deos not get better 4 23 Pathological Corneal Hypoxia What Happens with Lack of O2 to cornea epithelium >3.2% swelling of corneal tissue What is Swelling? 3 to 4 degree elevation in temperature Hypoxia – Anaerobic metabolism – Retention of lactic acid Hypercapnia – Build up of CO2 24 When you see microcysts and the ot says they see rainbow around light, the pt has pathological corneal edema. The temp of the cornea has increased so more anaerobic metabolism and retention of lactic acid The cysts tend to have clear centers so in the cyst there is fluid or cellular debris. 24 Stage 3: Epi Microcyst Edema w/ Chronic Hypoxia Un-resolved chronic edema “Rainbows” ?? > than 3.2% swelling ( Sweeney 1991) 15-50 um irregular shaped inclusion cyst Located epi layer,para-central to mid periphery Best seen in retro-illumination, 25x mag Collection of cellular debris & apoptotic cell Sign of altered metabolism Create discomfort as cysts surface & repurture 25 Microcystic edema à the level of edema has increased here leading to rainbow Rainbows usually happen due to increased motion in the atm. When you ask them to look at spot of light – there will be rainbow affect and they will see halo à the edema caused there to be moisture trapped in the cornea You can have them look at pinhole à and if it gets better vision then that’s good and its not as swollen When there is rainbow affect you have gone beyond the 3.2% acceptable edema 25 How large is a Microcyst 26 26 Stage 3 Edema: Epithelial Findings 27 Microcysts are easily seen in retro illumination. You will see pockets or sphere which are the cysts They will be anterior to the stroma and they are in epi layer and not deep in stroma 27 Stage 3: Epithelial Signs OD & OS Scleratic Scattered 28 This is a lot of microcysts and happens to ppl wearing hydrogel lenses and high minus lens where its thickest toward the edge of the optic zone and this will be over the mid-peripheral portion of the cornea which where there will be reduction of oxygen It can be seen mid-periphery for minus lens wear and for plus it can be seen centrally as well if the pt is wearing high + lenses. The oxygen transmission is depended on the how thick and thin the lens is over the specific area 28 Epithelial Microcystic Edema Microcyst:Translucent, irregular inter-epithelial cyst Best seen Retro-illum Located from epibasement layer to episurface >3.2% - epi cell loss Increased epi cell fragility: – slough off w rubbing or blinking – FB & dry sensation Periodic Erosion of epi cells causing pain Loss of epi surface compact nature, allowing for epi neo-vessels Loss of epi compact nature, pre-dispose cornea to opportunistic bacteria adherence 34 Loss of epi because they are older cells and they don’t have as much as strength as the younger ones Loss of the compact nature of the epi layer fluorescine shows the the cell border that has been lost 34