Modeling and Measuring Friction of the Leighton 10m Telescope

Estimating and identifying friction are important aspects of simulating a mechanical drive system. Accurate friction modeling helps to improve a telescope's performance. However, the friction conditions inside are complex and hard to measure. We did simulations with mathematical transfer functions for the Leighton 10 m Telescope and employed a polyline model to identify sources of friction. We made a two-stage model for the Leighton 10 m Telescope. Based on measurements of the motor's currents and speeds, we constructed a curve containing the friction information of the transmission elements. We simulated the system using a step function input under many combinations of friction parameters. By comparing simulation results with the measured ones, we determined the various friction components. This model accurately reproduced the telescope performance including the nonlinearities.

Eyelid malposition after orbital fracture surgery

Orbital fractures generally do not cause eyelid malposition.Studies have shown that mostly eyelid malposition is mainly due to the choice of surgical approaches of orbital fracture repair.Approaches are divided into transcutaneous and transconjunctival ones.The application of orbital fracture approaches depends on fractures’range and the surgeons’preferences.Eyelid malposition after orbital fracture surgery is not only an aesthetic concern but also a functional complication,which will cause eyes discomfort,such as corneal exposure and ocular irritation.Some patients may have multiple types of eyelid malposition.In this review,we summarized the surgical approaches of orbital fractures and the complications including scar,ectropion,retraction,entropion,flattening,laceration and lacrimal canaliculus avulsion and notch deformity that associated with eyelid,especially the lower eyelid.Reports revealed that the scar usually occurred in infraorbital incisions compared with subtarsal and subciliary incisions,and the transconjunctival approach had a higher incidence of entropion and flattening,and less ectropion than the transcutaneous approach.Meanwhile,pathogenesis of eyelid malposition after orbital fracture surgery are discussed.Furthermore,to prevent eyelid malposition complications,doctors should choose the appropriate orbital fracture approach according to the patient’s needs,and delicate tissue management,technical expertise,and meticulous hemostasis are necessary.Conservative treatment with taping,lubricating ointment,and steroid for eyelid malposition complications should be performed first,and then surgical intervention when the conservative treatment fails.

Periocular basal cell carcinoma-current treatment concepts

Basal cell carcinoma(BCC)is by far the most common human skin cancer.In Caucasians,BCCs account for around 90%of periocular malignancies.However,periocular BCCs are usually neglected due to their slow and painless growth,unless presenting complaints,e.g.,large size,bleeding,recurrent infections of the tumor,or secondary symptoms resulting from adjacent structures involvement as epiphora,limited eye globe motility as well as globe displacement.Moreover,although the tumor can usually be cured with local excision,local recurrence can occur in up to 20%of eyelid BCC cases.Recurrent BCCs of the eyelid show a poorer overall prognosis than the primary ones.In addition,the management of advanced diseases,such as orbital or intracranial invasion as well as metastatic lesions,is challenging and often involves a multidisciplinary approach.In this paper,we reviewed the recent research progress of pathogenesis,clinical presentation,and therapeutics of periocular BCCs.We introduced the molecular pathogenesis of BCCs[multi-step ultraviolet(UV)-induced carcinogenesis model,genetic predisposition,and epigenetic changes],clinical classification,and tumor-node-metastasis(TNM)clinically stage of eyelid skin BCCs.We also emphasized the treatment of BCCs,i.e.,surgical resection,oculoplastic reconstruction,and alternative therapies(radiation therapy,systemic therapy,topical therapy,and prophylactic therapy).In the end,we proposed that considering the possible iatrogenic damage to the surface of the eye by surgical excision,the treatment of periocular BCCs is recommended to be performed by or in the presence of an oculoplastic surgeon.

Three-dimensional anthropometry in periorbital region

Anthropometry can analyze the size,weight,and proportion of the human body objectively and quantitatively to supplement the visual assessment.Various non-invasive three-dimensional(3D)anthropometric techniques have been applied to assess soft tissues’3D morphology in the clinical practice.Among them,non-invasive stereophotogrammetry and laser scanning techniques are becoming increasingly popular in craniofacial surgery and plastic surgery.They have been applied for craniofacial growth estimation and morphometric investigation,genetic and acquired malformation diagnosis,as well as orthodontic or surgical treatment arrangement and outcome evaluation.However,few studies have been published for assessing the 3D morphology of soft tissues in the periorbital region.This paper reviews the studies involving the application and evaluation of the increasingly popular 3D photogrammetry in the periorbital region.These studies proposed detailed and standardized protocols for three-dimensionally assessing linear,curvilinear,angular,as well as volumetric measurements,and verified its high reliability in the periorbital region(even higher than caliper-derived direct measurements).In the future,reliable and accurate 3D imaging techniques,as well as standardized analyzing protocols,may find applications in following up morphological growth,preoperatively diagnosing and assessing patient periorbital conditions,planning surgical procedures,postoperatively evaluating treatment outcomes of a specific procedure,and comparing the differences in surgical results between various procedures,studies,as well as populations.

Socket discomfort in anophthalmic patients-reasons and therapy options

A smooth and timely fitting of a visually appealing,custom-made eye prosthesis after the loss of an eye is not only essential from a cosmetic point of view but above all facilitates good social and psychological rehabilitation.Cryolite glass prostheses must be replaced at least once a year,PMMA prostheses polished once a year and renewed every five years.In children,especially in growth phases,the fit of the prosthesis should be checked at least every six months and adjusted,if necessary.Ocularists and ophthalmologists should determine an individual cleaning procedure together with the patient,which depends on both the prosthesis material and external factors.Complications such as allergic,giant papillary,viral,and bacterial conjunctivitis or even blepharoconjunctivitis sicca must be detected and treated at an early stage to avoid discomfort and to maintain the ability of prosthesis wear.In the case of inflammation-induced shrinkage of the conjunctival fornices or post-enucleation socket syndrome,surgical interventions are necessary.In summary,an early supply with an eye prosthesis,adequate treatment of complications,and attention to psychological aspects,form the basis for a successful long-term rehabilitation of anophthalmic patients.

Ocular surface and tear film changes after eyelid surgery

Eyelid surgery is widely and extensively used in facial plastic and reconstructive surgeries.There are many categories of eyelid surgeries,the most common of which include blepharoplasty,ptosis surgery,and eyelid reconstruction.In many cases,these procedures are combined,and there are many different techniques for each type of operation.Upper eyelid blepharoplasty usually includes the excision of skin,preseptal orbicularis oculi muscle,and orbital fat.Common methods of lower eyelid blepharoplasty are the skin-muscle flap,the skin flap,and the transconjunctival.Ptosis surgery is mainly divided into three types:transcutaneous,transconjunctival,and sling surgery.Surgeons often used the Hughes or Cutler-Beard Bridge Flaps in eyelid reconstruction.Different types and methods of surgery have their own advantages and disadvantages,and postoperative complications may occur.Therefore,postoperative complications of eyelid surgeries,such as dry eye symptoms,should be taken into serious consideration.Relevant literature involving these complaints can be found in PubMed by searching the terms“dry eye”,“eyelid”,“surgery”,and other related keywords.Moreover,various ocular surface and tear film alterations may be detected using the Ocular Surface Disease Index(OSDI),tear film breakup time,Schirmer test,fluorescein staining,and lissamine green staining after various eyelid surgeries.As dry eye disease is prevalent in the general population,it is more urgent to figure out what we can learn from these complaints.Further exploration in this field may help surgeons to choose a better surgical method and give an accurate evaluation of the postoperative effect.

A UV-related risk analysis in ophthalmic malignancies:Increased UV exposure may cause ocular malignancies

Purpose:To explore the role of ultraviolet radiation(UVR)in the occurrence and development of various ocular malignancies.Methods:In this article,we retrieved ocular malignancy data from the Global Cancer Observatory(GCO)and performed correlation analysis with the global UV index and sunshine duration.We searched for associated studies using the following databases:Embase,Pubmed,Cochrane Library,and Google Scholar.We conducted the literature by searching the Mesh terms denoting an exposure of interest("UV radiation","ultraviolet rays",and"ocular malignancies"),All studies included are published until December 30,2023 without language restrictions.Results:The mechanisms and epidemiological statistics of UVR on the onset and progression of eyelid malig-nancies are the most studied and clear.The role of UVR in conjunctival melanoma is similar to that in eyelid melanoma.The relationship between uveal melanoma and UVR is controversial,however,it may have at least a certain impact on its prognosis.UVR causes ocular surface squamous neoplasia by further activating HPV infection.Conclusions:UVR is a decisive risk factor for ocular malignancies,but the incidence of ultraviolet-induced tumors is also affected by many other factors.A correct and comprehensive understanding of the mechanisms of UVR in the pathogenesis of ocular malignant tumors can provide patients with more effective and selective immune regulation strategies.

Personalized treatment concepts in extraocular cancer

Background:The periocular skin is neoplasms-prone to various benign and malignant.Periocular malignancies are more aggressive and challenging to cure and repair than those in other skin areas.In recent decades,immuno-therapy has significantly advanced oncology,allowing the autoimmune system to target and destroy malignant cells.Skin malignancies,especially periocular tumors,are particularly sensitive to immunotherapy.This tech-nique has dramatically impacted the successful treatment of challenging tumors.Main text:Extraocular cancers,including eyelid(basal cell carcinoma,squamous cell carcinoma,melanoma,merkel cell carcinoma),conjunctival tumors(conjunctival melanoma,ocular surface squamous neoplasia)and other rare tumors,are unique and challenging clinical situations.Several genetic alterations associated with the pathogenesis of these diseases have been identified,and molecular mechanism are essential for the development of the immunotherapy agents,such as Hedgehog pathway inhibitors(vismodegib and sonidegib)for basal cell carcinoma,BRAF/MEK inhibitors(vemurafenib,dabrafenib,and encorafenib)for melanoma,and immune checkpoint inhibitors(Avelumab,pembrolizumab)for Merkel cell carcinoma.Conclusions:The optimal treatment for periocular skin cancer depends on the type and size of the tumor and whether it involves orbital and adnexal structures.Adjuvant and neoadjuvant therapy with chemotherapy-targeted therapies and immune checkpoint inhibitors should be considered based on tumor type,tumor molec-ular profile,expected response rate,and candidacy for systemic treatment.

Global incidence and prevalence of malignant orbital tumors

Purpose:Aims to provide an overview of the contemporary epidemiology of malignant orbital tumors by analyzing population-based incidence patterns across various regions worldwide.Methods:In this article,we retrieved orbital malignancy data from the MEDLINE database and analyzed the incidence and prevalence of orbital malignancies worldwide.We performed the literature search by searching on the Mesh terms for malignant orbital tumors("orbital","tumor","lymphoma","malignant","cancer","incidence",and"epidemiology").All included studies were published between 1993 and 2023 and were written in English.Results:Ocular or ophthalmic lymphoma most frequently occurred in the orbit,with a prevalence ranging from 47%to 54%.The incidence of malignant orbital tumors was increasing in the USA 2.0 per million(1981–1993),Netherlands(0.86(1981–1985)to 2.49(2001–2005)per million)and South Korea(0.3–0.8 per million(1999–2016)),respectively.Ophthalmic lymphoma which includes orbit lymphoma was increasing in Canada(0.17–1.47 per million(1992–2010)),Denmark(0.86 per million(1981–1985)to 2.49 per million(2001–2005)),respectively.Conclusions:The predominant primary malignant orbital tumor in adults was lymphoma.Ocular or ophthalmic lymphoma most frequently occured in the orbit.The limited data available suggested an increasing trend in the incidence of malignant orbital tumors in each country included,which were mainly attributed to the increase in lymphoma.Generally,incidence rates were found to increase with advancing age,with no difference between males and females.

Personalized treatment approaches in intraocular cancer

Background:Intraocular malignant tumors represent a severe disease that threatens vision as well as life.To better extend the life of the patient,preserve visual function,and maintain ocular aesthetics,selecting the appropriate timing and methods of treatment becomes crucial.Main text:With the continuous advancement of medical technology,the techniques and methods for treating intraocular malignant tumors are constantly evolving.While surgery was once considered the optimal method to prolong patient survival and prevent local recurrence,the discovery and application of various treatments such as radiotherapy,laser therapy,chemotherapy,cryotherapy,and monoclonal antibodies have led to a greater di-versity of treatment options.This diversity offers more possibilities to develop personalized treatment plans,and thereby maximize patient benefit.This article reviews the various treatment methods for intraocular malignant tumors,including indications for treatment,outcomes,and potential complications.Conclusions:Differentiating small intraocular malignant tumors from pigmented lesions is challenging,and ongoing monitoring with regular follow-up is required.Small to medium-sized tumors can be treated with radiotherapy combined with transpupillary thermotherapy.Depending on the tumor's distance from the optic disc,surgery with partial resection may be considered for distant tumors,while proximal tumors may require complete enucleation.Systemic chemotherapy has been widely applied to patients with retinal tumors,lym-phomas,and intraocular metastatic cancers,but has limited efficacy in patients with choroidal melanoma.An-tagonists of Vascular Endothelial Growth Factor(Anti-VEGF)drugs can improve patient vision and quality of life,while the efficacy of immunotherapy and molecular targeted therapy is still under research.

Lateral tarsal strip procedure for involutional ectropion: A retrospective analysis of 85 cases and a comprehensive literature review

Purpose:To evaluate the postoperative effect of the lateral tarsal strip(LTS)procedure in treating lower eyelid involutional ectropion.Methods:A retrospective study was performed on 85 eyelids in 67 patients with involutional ectropion who underwent LTS procedure.Pre-and postoperative lower eyelid laxity and ocular symptoms as well as perioperative complications were evaluated.Snap back test was performed to evaluate the elasticity of lateral canthal tendon loosening and,a lower lid distraction test was performed to evaluate the degree of severity before surgery.Ocular surface diseases were evaluated by the Ocular Surface Disease Index(OSDI),and symptoms including conjunctivitis,corneal ulcer,dry eye syndrome,and ocular pain were recorded.All patients were evaluated within one week and during the follow-up period of 4.2
8.3 months.Furthermore,we reviewed the studies that also investigated the surgical effect of the LTS procedure in the literature from 1979 to 2019.Results:The success rate was 95%.Only four eyelids required a second surgical intervention.Seventy-three(86%)eyelids had an excellent position after surgery,9(11%)only little improvement,and three had no improvement.No significant difference was found in the postoperative effects between different degrees of ectropion(p>0.05).No statistical correlation was found between surgical improvements and the ectropion severity(P>0.05).Fiftytwo out of 85 eyes had no discomfort after the surgery.Mild complications included epiphora in 13 eyes(three cases caused by lacrimal punctum eversion),ocular pain in 12 eyes,wound hemorrhage in 12 eyes,and edema in 9 eyelids immediately after surgery,in which 91.2%(n=21)disappeared within one week and did not need any further treatment.Conclusions:The lateral tarsal strip procedure can provide an aesthetically pleasing result for correcting the mild to moderate lower eyelid ectropion while maintaining decent eyelid function.