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Dr. Peter A. Karth is a board-certified ophthalmologist and a vitreo-retinal specialist and surgeon, Dr. Karth is currently on the faculty of the Stanford University School of Medicine, Department of Ophthalmology as a Assistant Clinical Professor at The Byers Eye Institute.

With specific focus on minimally invasive small incision sutureless and painless surgery for delicate procedures such as floaters removal, macular holes, epiretinal membranes and macular pucker, Dr. Karth leverages his experience to focus on successful outcomes and a superior patient experience at every step. In the clinic, Dr. Karth and his team focus on providing cutting-edge patient care and the unparalleled patient experience in the diagnosis and treatment of macular degeneration, diabetic eye disease and retinal vascular occlusions. Dr. Karth has implemented clinic standards to reduce patient wait times, improve outcomes, provide vision-saving care to all his patients.

OVERVIEW - As a board-certified ophthalmologist and a vitreo-retinal physician and surgeon, Dr. Karth is currently on the faculty of the Stanford University School of Medicine, Department of Ophthalmology as a Assistant Clinical Professor at The Byers Eye Institute. Dr. Karth has had excellent training in vitreoretinal surgery and disease. He underwent Retinal Fellowship training at the renowned Byers Eye Institute at Stanford University in Palo Alto, California. He has previously completed his surgically intense ophthalmology residency at Medical College of Wisconsin in 2013. Dr. Karth attended the ​University of Illinois at Chicago where he received his MD degree while concurrently completing his MBA degree at University of Chicago Booth School of Business where he concentrated in Entrepreneurship, Management, and Finance. Dr. Karth has contributed to many popular and peer-reviewed ophthalmic publications and has given several research presentations at national and international meetings. He is interested in medical device innovation, medical informatics applications, and healthcare clinical efficiency. Dr. Karth is a devoted clinician and surgeon.

Clinical Focus

  • Ophthalmology
  • Retina
  • Retina surgery
  • Macular Degeneration
  • Diabetic eye disease
  • Retinal Detachment
  • Macular edema
  • Retinal eye screenings

Academic Appointments

Professional Education

  • Fellowship:Stanford University Hospital and Clinics (2015) CA
  • Board Certification: Ophthalmology, American Board of Ophthalmology (2014)
  • Internship:St Francis Hospital-Evanston (2010) IL
  • Residency:Medical College of Wisconsin (2013) WI
  • Medical Education:University of Illinois at Chicago College of Medicine (2009) IL


All Publications

  • Short-Term Outcomes of Aflibercept Therapy for Diabetic Macular Edema in Patients With Incomplete Response to Ranibizumab and/or Bevacizumab. Ophthalmic surgery, lasers & imaging retina Wood, E. H., Karth, P. A., Moshfeghi, D. M., Leng, T. 2015; 46 (9): 950-954


    Aflibercept is a vascular endothelial growth factor (VEGF) inhibitor recently approved by the U.S. Food and Drug Administration for the treatment of diabetic macular edema (DME). Currently, the effect of switching to aflibercept from other anti-VEGF agents for DME is unknown.In this prospective, interventional case series, DME patients with persistent retinal fluid despite regular (every 4 to 6 weeks) intravitreal injection (IVI) with ranibizumab 0.3 mg, and/or bevacizumab 1.25 mg were switched to IVI aflibercept 2 mg. Collected data included visual acuity, central subfield foveal thickness (CSFT), and the area of thickest edema on registered spectral-domain optical coherence tomography (SD-OCT).At 1 month after the first aflibercept IVI, 79% (11 of 14 eyes) showed anatomic improvement with a 23% decrease in average CSFT from 421 µm to 325 µm (P < .0132).A majority of patients with DME with persistent fluid on SD-OCT despite regular ranibizumab 0.3 mg and/or bevacizumab 1.25 mg IVIs showed a positive anatomic response to IVI aflibercept 2 mg. [Ophthalmic Surg Lasers Imaging Retina. 2015;46:950-954.].

    View details for DOI 10.3928/23258160-20151008-08

    View details for PubMedID 26469235

  • Incontinentia Pigmenti: A Comprehensive Review and Update OPHTHALMIC SURGERY LASERS & IMAGING RETINA Swinney, C. C., Han, D. P., Karth, P. A. 2015; 46 (6): 650-657


    Incontinentia pigmenti (IP) is a rare syndrome with skin lesions, ocular abnormalities in the retina and elsewhere, central nervous system abnormalities, and teeth defects. The authors present an updated review of the literature, highlighting diagnosis, epidemiology, pathophysiology, clinical features, and management of IP. IP is an X-linked dominant syndrome with an incidence of 0.0025%; most patients are female. IP is caused by a mutation in the IKBKG gene, causing a loss of function of NF-κß, leaving cells susceptible to apoptosis from intrinsic factors. The cardinal feature of IP is four stages of skin distinctive lesions. Of those with IP, 36.5% have detectable eye pathology and 60% to 90% of those have retinal issues. Peripheral avascularity and macular occlusive disease commonly occur. The authors performed a comprehensive review of Medline from 1947 to 2014. All papers mentioning IP in ophthalmologic journals were reviewed as well as applicable publications from other medical specialties.

    View details for DOI 10.3928/23258160-20150610-09

    View details for Web of Science ID 000359292700009

    View details for PubMedID 26114846

  • Multimodal Imaging of Posterior Dislocation of Crystalline Lens Nucleus following Vitrectomy. Journal of ophthalmic & vision research Karth, P. A., Swinney, C. C., Montague, A. A., Moshfeghi, D. M. 2015; 10 (2): 197-199

    View details for DOI 10.4103/2008-322X.163785

    View details for PubMedID 26425326

  • Assessing photoreceptor structure after macular hole closure. Retinal cases & brief reports Hansen, S., Batson, S., Weinlander, K. M., Cooper, R. F., Scoles, D. H., Karth, P. A., Weinberg, D. V., Dubra, A., Kim, J. E., Carroll, J., Wirostko, W. J. 2015; 9 (1): 15-20


    To describe photoreceptor structure and recovery after macular hole (MH) closure with pars plana vitrectomy (PPV) using adaptive optics scanning light ophthalmoscopy and spectral domain optical coherence tomography.A pilot imaging study of four eyes from four subjects undergoing PPV for MH was conducted. Imaging with spectral domain optical coherence tomography and adaptive optics scanning light ophthalmoscopy was performed at varying time points after PPV.Despite successful MH closure, disruption of the foveal inner segment ellipsoid zone was seen in all patients when imaged at a mean of 117 days after PPV. Disruption of the photoreceptor mosaic was seen using adaptive optics scanning light ophthalmoscopy at locations corresponding to regions of ellipsoid zone disruption on spectral domain optical coherence tomography. Cone density immediately surrounding these disruptions was normal, except for one patient. In 2 patients who were imaged serially up to 516 days after PPV, recovery of cone cells within regions of mosaic disruption could be detected over time.Photoreceptor disruption exists even after apparent MH closure. Remodeling of the foveal cone mosaic continues for many months after surgery, perhaps accounting for the delayed postoperative improvements of visual acuity in some patients. Spectral domain optical coherence tomography and adaptive optics scanning light ophthalmoscopy are useful tools for monitoring photoreceptor recovery after surgical closure of MH.

    View details for DOI 10.1097/ICB.0000000000000117

    View details for PubMedID 25525907

  • Spectral-Domain Optical Coherence Tomography of Emulsified Subretinal Silicone Oil Presenting as a Macular Inverted Pseudohypopyon OPHTHALMIC SURGERY LASERS & IMAGING RETINA Karth, P. A., Moshfeghi, D. M. 2014; 45 (5): 437-439


    The authors present a rare case of an inverted pseudohypopyon due to subretinal emulsified silicone oil in the macula of a patient who underwent pars plana vitrectomy surgery for repair of retinal detachment with proliferative vitreoretinopathy 1 year prior to presentation of this finding. The patient’s predisposing diagnosis is pathologic myopia.

    View details for DOI 10.3928/23258160-20140908-05

    View details for Web of Science ID 000347297300011

    View details for PubMedID 25215873



    To describe surgical outcomes of macular telangiectasia (MacTel) Type 2 associated full-thickness macular holes (FTMH) in 4 patients and to review the literature.Retrospective interventional case series with a review of medical records, including optical coherence tomography.One eye of each patient underwent pars plana vitrectomy with internal limiting membrane peeling, gas tamponade, and prone positioning. In 2 patients, the holes did not close (final visual acuity: 20/70 and 20/200). In 1 patient, the hole reopened after 4 months (final visual acuity: 20/400). In the fourth patient, the hole remained closed (final visual acuity: 20/30). In contrast to the failed cases with large retinal cavitations seen on optical coherence tomography before FTMH formation, the successful case had small intraretinal cavitation before FTMH development, and the appearance of FTMH being similar to typical idiopathic FTMH. Adding these cases to the limited published reports resulted in closure rate of 30% for FTMH associated with MacTel.Since surgical outcomes for FTMH in MacTel Type 2 may be less successful than typical idiopathic FTMH, it is important to recognize that FTMH may be associated with MacTel. Lower success rate may be because of the pathophysiology of MacTel. The degree of tissue atrophy and appearance of FTMH on optical coherence tomography may guide surgical prognosis.

    View details for Web of Science ID 000337148700008

    View details for PubMedID 24270919

  • Paired responses to intravitreal bevacizumab in diabetic macular edema: predictors of response in the fellow eye GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY Karth, P. A., Chang, A., Wirostko, W. 2014; 252 (2): 207-211


    Factors predictive for response of diabetic macular edema (DME) to intravitreal bevacizumab (IVB) remain unclear. In this study, we assess the predictability of DME response to IVB based on the response to IVB in a previously treated fellow eye and other known pre-injection factors in (DME).Retrospective chart review was conducted on 28 patients (56 eyes) with bilateral DME who underwent bilateral IVB therapy. Responses in both eyes were measured by change in central subfield thickness (CSFT) via optic coherence tomography (OCT), and change in visual acuity. Age, lens status, and starting macular thickness were recorded.We found 21 % of the reduction in CSFT after IVB on OCT in the study eye may be explained by the percentage change in CSFT in the previously treated fellow eye [CI: 0.092-0.716; p-value = 0.0141]. Also, the pre-injection CSFT predicts 14 % of the response to IVB in the same eye [R² = 9.6 %, p-value = 0.018]. When combined in a multi-factorial model, 33 % of the change in CSFT following IVB may be explained by these two factors. Lens status, change in visual acuity, and age were not statistically significant predictors of response.In DME, the response to IVB in an eye is partially explained by the pre-injection retinal thickness in the same eye and by the response to IVB in the previously treated fellow eye. Lens status, change in visual acuity, and age were not statistically significant predictors of response in this study.

    View details for DOI 10.1007/s00417-013-2422-4

    View details for Web of Science ID 000330994600003

    View details for PubMedID 23873254

  • Branch retinal artery occlusion after internal carotid artery angioplasty and stenting. Retinal cases & brief reports Karth, P. A., Siddiqui, S., Garbett, D., Stepien, K. E. 2013; 7 (4): 402-405


    A 67-year-old man with an embolic branch retinal artery occlusion occurring as a complication of internal carotid artery stenting, despite the use of a distal filter cerebral protection device was reported.Observational case report. One patient case is included in this case report.The patient developed a branch retinal arterial occlusion with visible emboli 24 hours after a carotid angioplasty and stenting procedure and was found to have multiple anastomoses between the external carotid artery and ophthalmic artery as a result of carotid stenosis. He required a second, emergent angioplastic procedure.External carotid-ophthalmic arterial anastomoses can act as a pathway for emboli to travel from the internal carotid artery to the retinal circulation, resulting in retinal arterial occlusions, despite the use of cerebral protective devices. Ophthalmologists and interventional radiologists should be aware of these factors, especially as the number of percutaneous carotid artery stenting procedures continues to increase.

    View details for DOI 10.1097/ICB.0b013e318298bda1

    View details for PubMedID 25383818

  • Endophthalmitis following photorefractive keratectomy with a history of radial keratotomy: a case report. Journal of ophthalmic inflammation and infection Karth, P. A., Karth, J. W. 2013; 3 (1): 31-?


    We report the case of an 81-year-old woman with a history of radial keratotomy 9 years prior who developed endophthalmitis without preceding keratitis 4 days after uneventful photorefractive keratectomy surgery. This case report utilized clinical examination and microbacterial laboratory findings.Diagnosis of bacterial endophthalmitis was made via clinical examination and cultured vitreous tap which grew methicillin-resistant Staphylococcus aureus. No preceding keratitis was seen on exam. The patient responded to intravitreal antibiotics.We believe that the epithelium removed during the photorefractive keratectomy procedure may have uncovered areas of full-thickness radial keratotomy incisions allowing bacterial ingress, causing bacterial endophthalmitis without preceding keratitis.

    View details for DOI 10.1186/1869-5760-3-31

    View details for PubMedID 23514571

  • Bilateral central retinal artery occlusions in an infant with hyperhomocysteinemia JOURNAL OF AAPOS Karth, P., Singh, R., Kim, J., Costakos, D. 2012; 16 (4): 398-400


    A previously healthy 7-week-old boy developed bilateral central retinal artery occlusions in the presence of hyperhomocysteinemia and elevated serum methylmalonic acid and was found to have a transcobalamin receptor mutation. Retinal arterial occlusion is uncommon in young patients and typically prompts a systemic workup. In cases of atypical retinal arterial occlusion, hyperhomocysteinemia should be investigated.

    View details for DOI 10.1016/j.jaapos.2012.04.003

    View details for Web of Science ID 000309503600020

    View details for PubMedID 22819238

  • Effects of Green Diode Laser in the Treatment of Pediatric Coats Disease AMERICAN JOURNAL OF OPHTHALMOLOGY Shapiro, M. J., Chow, C. C., Karth, P. A., Kiernan, D. F., Blair, M. P. 2011; 151 (4): 725-731


    To review the effect of green diode laser ablation therapy on retinal structure and functional outcome in patients with advanced Coats disease.Retrospective, interventional case series.Fourteen eyes of 13 patients with Coats disease were included in this study. Medical records, Retcam photographs (Clarity Medical Systems, Pleasanton, CA), and fluorescein angiograms were reviewed. All patients initially were treated with green diode laser (532 nm) ablation therapy to areas of the retinal telangiectasis associated with exudation. Main outcome measures included visual acuity, treatment outcome defined as complete resolution of telangiectatic lesions or exudative detachment, and macular status at the end of follow-up.Before treatment, 1 eye was at stage 2 (telangiectasis and exudation), 12 eyes were at stage 3 (exudative retinal detachment), and 1 eye was at stage 4 (total retinal detachment with glaucoma). Five eyes had highly detached retina of more than 4 mm. Median age at diagnosis was 51 months (range, 0.5 to 153 months). Median follow-up was 39.5 months (range, 15 to 70 months). Median number of green diode laser photocoagulation treatments was 2 (range, 1 to 5). After laser photocoagulation, 13 (93%) of 14 eyes had no active exudation. Functionally, 4 (29%) of 14 eyes had 20/50 or better visual acuity, 3 (21%) of 14 eyes had 20/60 to 20/200 visual acuity, 5 (36%) of 14 eyes had 20/400 to light perception visual acuity, and 2 (14%) of 14 eyes had no light perception visual acuity. No eye was phthisical or enucleated.Green diode laser therapy can be an effective treatment for advanced Coats disease, even in the presence of a moderate to severely elevated retinal detachment.

    View details for DOI 10.1016/j.ajo.2010.10.024

    View details for Web of Science ID 000288974700024

    View details for PubMedID 21257148